List your favorite supporting character. Why they are your favorite and what game are they from.
Mine is Isono from Sharin no Kuni. Dude is freakin’ awesome. His randomness is hilarious and his character is quite good at keeping an aura of mystery around him. My second favorite is probably Chousen from Kohime. Again just because he is hilarious as a comic relief.
Otonashi Ayana from Subarashiki Hibi. She stands on the edge, gazing down at the world.
Second, probably Gumoruku from Mugen Kairou (1 + 2). Gumoruku is great.
I actually wanted to make a thread like this when I realized that I couldn’t think of a great eroge protagonist, but could easily name a dozen decent supporting characters.
My favorite would be Suginami from Da Capo II, he is absolutely awesome, he made that pretty mediocre game worth my money. Suginami from the first game was great, but the “Mark II” is just plain perfect. Character art and voice acting fit each other like a glove. Dialogues are side-splittingly funny. It’s too bad that the story of his rivalry with Mayuki wasn’t explored as much as I’d like.
Another great, great sidekick is Murakami from KIRAKIRA. Overdrive sure know how to create comedy relief characters (all guys from Edelweiss are fantastic too), but Murakami takes the cake, mainly due to insane character art and personality/appearance mismatch that made me literally LOL so many times.
yeah he made me laugh my ass off
the dad from family project and the best friend from my girlfriend is president have also made me laugh kuu was good as well
I wished Murakami was the protag, I liked him so much better! 
(Well, him as protagonist might not completely work - how about me as a female sidekick protagonist helping him get together with people?)