Continuous growth - a body so good that even straight guys think about it. Also ALWAYS on the lookout for opportunities to eat/absorb muscle cum, administered any way the donor finds is the most pleasurable for him.
Hwang Chul-Soon, Jo Seung Min, David Laid, Jeff Seid, Lu Chen Hui
Got Any Fetishes?
Male Cum Pregnancy (Mpreg - but usually with the resulting effect of extreme muscle growth by the impregnee), Muscle growth, forced cumming, forced growth, spiked cum, edging, brother/brother, dad/son, other family situations. Not a huge fan of explicit violence, but pain in the service of growth/dominations can work.