Hi. The next time, please wait more than 59 minutes to get a reply here before losing all hope as no one can be around 24/7, thank you. I'm happy to help but my availability at 2/3 am is nearly non-existent, I'm afraid!
As I can see your original post in the post history, I will now answer your question to the best of my ability. If you need any further clarification, please let me know. There is a summary at the end because I tend to ramble! Sorry.^^'
What you wrote:
"I need your help explaining something I don't understand (I have a hard time comprehending stuff that's not simplified) did Vincent care about O Ciel or only care about R Ciel because I Read someone that Vincent called O Ciel a "spare" when Francis asked "who would inherit the manor the title"
and stuff and that he had high regards for the R Ciel instead of O Ciel and it throws me off because people tell me he's bad people tell me he's good people tell me he only cares about R Ciel I don't get it and I have like heard so many yes and no’s it’s confusing and the manga panel I read a few times confused me uh..."
Heir and Spare
First, I want to give some little context. Matters of inheritance were (and are) very serious matters in England, particularly within the aristocracy. As you have read in the Public School Arc, "tradition is everything" in England. The importance of nobles is very closely linked to tradition. Even if a noble family has little money left, they will still retain their social standing and (a certain) power and influence that is only available to those with a title. Families that have become rich due to, for example, establishing successful businesses will have a high, important standing in society, but never in the same manner as a titled family - even if said titled family is significantly less wealthy than them, simply because of the historical significance connected to titles and old family names.
(As such, rich families without titles and old aristocratic families with little money would often agree to marriage unions because the former need/want a title and the latter want/need money.)
Great wealth will bring power and influence, but titles (and lineage) are just extra special amongst the English upper class.
Therefore, it is very important to preserve aristocratic lineages and titles by securing the line of inheritance and succession with an heir and a spare. (Sometimes, when a couple has only married out of convenience, not for love, they would agree to have an heir and a spare together (preferably two boys, though girls could and did inherit too) before they would go their separate ways. They rarely divorced and simply went on to take lovers after their "duty" was done, and the matter of inheritance was settled.)
While "spare" is definitely not the nicest word to use to refer to your child, it still describes the child's "position" as their older sibling's "back-up" when it comes to matters of inheritance. "Spare" sounds unkind, but is, nonetheless, the technical term. If someone calls someone the "spare," they most often only dryly refer to that person's position within the line of succession. Whether someone means "spare" as an insult or so depends on the person and context, and how the spare is ultimately treated depends on their family.
There are families in which the spare is treated as "lesser," but there are also, of course, families that love all their children equally, no matter their birth order.
However, even if the "heir and spare" are loved equally, tensions, resentments, and such can still arise between them. The heir will be the only one to inherit the family properties and title after all, and the spare won't. They might be given the same amount of love, but society and inheritance rules might still be able to get between the siblings as they hinder them to be truly "equal". Even if they are treated normally within their family, the label of "heir and spare" that was given to them by society still exists, and being referred to as "the spare" in any capacity and no matter how technical it's meant can hurt after all.
Chapter 131 to 133
I think you specifically refer to this conversation from Chapter 132?
As you can see, Vincent never calls O!Ciel a spare here. Francis is the one who does. In the previous chapter, Diedrich also touches upon the topic of inheritance:
Vincent also does not call O!Ciel "the spare" at any point in the manga. Francis also calls O!Ciel "the spare" not to insult or belittle him - she uses it as the technical term. Francis and Diedrich also do not bring up this topic with the intention to hurt O!Ciel. They bring it up out of concern and because they are thinking practically: Francis worries that O!Ciel could never fulfil his place as the spare if anything happened to R!Ciel because of his asthma and frail constitution. Diedrich encourages O!Ciel to be cheekier because he will need to fight more to build the life he wants because he won't just be handed a land, money, and a title.
Vincent, on the other hand, completely dismisses the matter during the conversation with Diedrich, saying that O!Ciel and R!Ciel are only 7 and, thus, too young to worry about inheritances just yet.
During the conversation with Francis, Vincent replies with a sarcastic remark that he would have to "relinquish the Watchdog's duties and our estate to the crown". He is joking and not taking the matter seriously which makes Francis mad.
To Francis and Diedrich, this matter of inheritance is too important not to deal with immediately (and Francis was in the position of "the spare" herself; she knows how it is like to fulfil that role (to be the Watchdog's spare), and the topic might be particularly touchy and important for her as a result). To Vincent, however, it's unimportant right now. His children are still little after all. They should be educated, of course, for their roles, but it's nothing to get any headaches over.
Vincent is also very surprised to hear that his seven-year-old sons have been worrying about their futures and positions in society that much already in Chapter 133.
If Vincent truly cared about the "heir and spare" thing, his responses to Francis and Diedrich and his reaction to learning about the twins' conversation from Chapter 132 would have been very different. He would have been more serious, either agreeing with Francis or showing that he is seriously thinking about her words. He would have agreed with Diedrich and encouraged O!Ciel to be cheekier too. He would have thought that it's good for his sons to have such a heavy conversation at age 7 because it's "never too young to worry about the future!" or anything like that. But Vincent does not do any of these things.
He does not care about the "heir and spare" nonsense. He just cares about his sons.
(Vincent also does not care about traditions much: His sons have "unusual" names that pissed off his traditional relatives but he did not care. As he says in Chapter 132, "an era in which traditional English names are thought to be tedious might not be too far-off." Though he refers to English names here in particular, this still shows his disregard for tradition and could be applied to other aspects too.)
Furthermore, the twins are treated the same.
They are put in the same clothes. Toys are bought in double. They sleep in the same room with identical beds. They receive the same education. Both R!Ciel and O!Ciel get educated in kingcraft (as mentioned in Chapter 132) which is "the art of governing as a king" (= how to look after their lands and the people that live on it), and both accompany Vincent to learn more about kingcraft "out in the field" in the same chapter. (He also takes both twins to parties to mingle; for example, he took them to the party where they met Kelvin.) O!Ciel isn't left out of these lessons and outings.
Of course, O!Ciel's health prevents him from certain things, but when he feels well and healthy, he has the same options as his brother. For example, in Chapter 131, O!Ciel was not prevented to go boating with his family because he is "the spare"; he couldn't go because his asthma was still acting up and because he told his family to go without him. And when his parents and brother returned, they brought him flowers to cheer him up.
There is ultimately no difference in how the twins are treated by Vincent (and Rachel), and they are both loved by their parents.
Perceptions
However, while Vincent objectively loves both his sons and does not think of them as his "beloved heir and the stinky extra spare," O!Ciel still obviously struggled/struggles with his position as "the spare".
O!Ciel believed everyone only thought of him as "the spare" and did not like him as they liked R!Ciel. That's what drove to "steal" his brother's name: He genuinely didn't think anyone would be happy if only "the spare" returned and the heir did not.
The flashback chapters are told from O!Ciel's point of view and are, thus, influenced by how he perceived everything. He feels insecure because he is sickly and shy, whereas his brother is healthy and lively. Diedrich's words hit a nerve, and O!Ciel runs away without continuing to listen to the conversation. As a result, it's unknown how the conversation continued. If Vincent had defended/praised/etc. him later him, O!Ciel would not have known, for example. O!Ciel overheard the conversation between his aunt and father: He was never meant to hear it. If Francis had known that he was listening, she might not have called him "the spare" or reassured him that she does not mean it as an insult and is only concerned for him. It was a conversation between adults, and O!Ciel could not interpret it correctly yet.
(Just like he could not interpret Sebastian the dog's actions correctly: He thought that the dog barked at him and dragged him by the clothes and pushed him with his nose because he didn't like him when Sebastian did all that to make sure O!Ciel was safe.)
Because O!Ciel's backstory is told from his view, it is easy to take his misinterpretations at face value or to forget that there is a lot O!Ciel simply does not know. O!Ciel thinks his father (and everyone else) likes R!Ciel more, so it becomes easy for readers to believe that this is true when it's not. O!Ciel also cannot look into his father's head; Vincent's (and everyone else's) direct thoughts are, thus, missing from the flashbacks.
Lastly, while Vincent undoubtedly loves his children, this does not automatically mean that he is a good parent. I have read a few posts that criticise Vincent for, for example, not saying a word when O!Ciel was too sick to go on that boating trip. I'm not sure if you have come across such posts too, but if you did, please keep in mind that parenting mistakes do not mean that a parent hates/dislikes their child. It just means they're not perfect, no that they don't have any love or regard for their child.
(I won't go into whether Vincent was a "good" or a "bad" parent because I think that's up to everyone's own interpretation.)
TL; DR
The passing down of properties and titles is serious business amongst English nobles.
"Heir and the spare" is a technical term and not necessarily meant as insults.
The treatment of the "heir and the spare" varies depending on the family.
Being called "the spare" by anyone will hurt, even if you are showered by love by the people that matter.
Vincent never called O!Ciel "the spare" and never thinks of him as such.
Vincent did not care about "the heir and the spare" stuff or tradition. He just wanted his kids to be kids (for now).
Vincent loved both his sons. He did not like one more than the other.
Vincent may have still sucked as a parent, but that's up to you to decide.
(Sucking/Making mistakes as a parent =/= hating your children)
Now, this ended up super long^^' I'm sorry! I hope it was still understandable/made sense. And as I said earlier, please feel free to tell me if anything is unclear!
