there is just something so comforting about pegoryu. ryuji is the first person akira meets when he gets to shujin, he's the first person to show him kindness, and he's a big part of the reason akira awakens his persona in the first place. the two just click for me! i also think they're two different brands of "delinquent," and it's always interesting to put the stylish, rogue-type next to the more boyish, crass one and see what happens. akira's not so uptight that ryuji would bother him, though, and that's what makes it work.
these two also have some of the gayest lines in the series, in my opinion.