I suggest you using tags to find a specific genre of yaoi you want. But otherwise, I recommend Viewfinder (i'm sure you've heard this or might already read it.) and http://www.mangago.me/read-manga/yandere_hitotsu_yane_no_shita/
BDSM:
webtoons:
http://www.mangago.me/read-manga/blood_bank/
http://www.mangago.me/read-manga/from_points_of_three/
manga:
http://www.mangago.me/read-manga/love_me_hard/
http://www.mangago.me/read-manga/ai_subeki_sadist/
http://www.mangago.me/read-manga/kaineko/
http://www.mangago.me/read-manga/sm_gokko/
http://www.mangago.me/read-manga/sadistic_boy/
serious manga(beating/humiliation/realistic):
http://www.mangago.me/read-manga/yoru_wa_tomodachi/
http://www.mangago.me/read-manga/sneaky_red/
yandere:
http://www.mangago.me/read-manga/color_recipe/
http://www.mangago.me/read-manga/akuma_chan_wa_momoiro/
http://www.mangago.me/read-manga/deichuu_no_hasu/
http://www.mangago.me/read-manga/doushiyoumonai_renjo/
http://www.mangago.me/read-manga/sakura_gari/
http://www.mangago.me/read-manga/escape_into_oblivion/
http://www.mangago.me/read-manga/scarlet/
Any yaoi manga recommendations with BDSM theme Or a yandere character ? Thanks a lot !!