My little brother was made fun of because of his drawings, what should I say to comfort him?

He's about 15 and loves to draw always has but recently he gets secretive about what he's been drawing, will like even try hide them but i am nosy ill admit so i do peak around now and then lol. So the other day I went to go get him from school and he was upset because people had made fun of him or something. I asked why and what for and he said my drawings. He then quite nervously gave me his art book and said '' I want you to have a look but don't tell anyone okay..'' okay sure I promise I said.

I don't know why but I was expecting like violent stuff, but it really was quite the opposite actually. just lots of drawings of anime guys and blushing faces lol which I thought was cute, and as I continued looking the guys became more visual and seemed softly erotic. and some of the characters even looked a bit like him.

He kinda had his head down the whole time while i was looking but i just said something like '' dude these are really nice, good job but I do think these guys are missing some girls in there too, maybe you should draw some too.'' and he kinda went mmm mm yea il try

I think he's still a bit down though so what else should i do?
My little brother was made fun of because of his drawings, what should I say to comfort him?
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