In analyzing Matt and Vincent, to me the most prominent element is their acceptance in society, or rather, the lack of such inclusion. Both are brought into this world in ways that are a minority in their society. Similarly, both of the protagonists had no control over the situation they were put into. In both cases, their "abnormal" birth was the decision of others, and yet they were the ones paying the price. Along with this comes one of the largest differences between the two: Matt is ostracized for being genetically created, and Vincent is ostracized for not being genetically created. This relates to the setting the two characters are in, and how it affects them.
Something I found interesting is that both "worlds" were very sic-fi and high-tech, and yet genetic creation was only accepted in one of the two stories. Throughout the novel, the sci-fi setting in comparison to the acceptance of genetic modification was able to hint at morals, values, and twist around the relationships between Matt/Vincent and the other characters. This played a large role in how isolated the characters were, as Matt's isolation from reality is quite an opposite to Vincent's role in "normal" life.
Along with this comes another difference. Matt never physically changed into something or someone different, and he remained a clone, and was challenged with having to accept that. Vincent, however, took a seemingly more active role and modified who he was to try and physically abolish what differentiated him from the majority, to forcefully gain the acceptance and equality that both characters wanted.
Passion, on the other hand, was something the two did share. In Matt's case, Maria, as well as Celia and Tam Lin, drove him to do certain things and make certain choices, and Vincent's relation with Irene was quite similar. Vincent's determination to get to space could also be connected back to Matt's goal of restoring morality. Although these motives had similar outcomes, the way the characters achieve things varied drastically. In my opinion, this is largely due to the fact that Matt is young and quite unaware of reality for most of the story, whereas Vincent is a mature man thoroughly integrated into society. A clear example of Matt's case is "Another picture showed a man holding a bullfrog between two slices of bread. RIBBIT ON RYE! the caption said. Matt didn't know what a ribbit was, but Celia laughed every time she looked at it (Farmer 8).". However, in the end both characters seem to experience similar moments and decisions, maybe not physically, but emotionally and mentally.
As the audience (reader/viewer), the determination, boldness, risk-taking nature, and deep thinking is obvious when either character faces a crossroad or a challenge. In terms of deep thinking and emotional intensity, a sentence that really proved this for me about Matt was "Matt wished desperately that he could get over things that fast. Whenever he was hurt of angry or sad, the feelings stuck their claws into him until they were ready to let go (Farmer 66).". In the end, I think it is not the two characters' lack of acceptance in society that connects them. Rather, I believe it is how they faced this, which includes both their actions and reactions. Though they physically may differ, their hearts beat quite the same.