http://www.mangago.me/read-manga/kawaii_akuma/ tries to trick him, and when it doesn't work he improvises...its more forced into a relationship but it may qualify...
http://www.mangago.me/read-manga/hidoku_shinaide/ blackmails him into a relationship.
http://www.mangago.me/read-manga/hua_hua_you_long/ its a bit darker blackmail/rape ect...not so much my cup of tea but its very well liked.
http://www.mangago.me/read-manga/datte_maou_sama_wa_kare_ga_kirai/ its sorta ridiculous the seme is our hero who's come to subjugate the demon king....its all played for laughs but there's blackmail...ish
http://www.mangago.me/read-manga/feng_yu_jiu_tian/ threatens and bullies....
http://www.mangago.me/read-manga/madness/ kidnapping threatening...and he's sorta a sociopath...and that sorta never changes.
http://www.mangago.me/read-manga/kichiku_encount/ uke is sorta bullied into a relationship but the last chapter is supe sweet...ok he's still a terrible human but it's somehow cute...
http://www.mangago.me/read-manga/kohitsuji_project/ shounen ai, bullies at first
http://www.mangago.me/read-manga/ai_to_yokubou_wa_gakuen_de/ a bit of everything in this, its also fairly funny....
http://www.mangago.me/read-manga/sick/ bullies
these are some I have a more complete bully list
http://www.mangago.me/home/mangalist/60580/?filter=&page=3 but a lot of them are sadistic semes so bullies or teases wthroughout the whole manga. I tried to pick some that just started with bullying or threats or blackmail.
thank you! (⌒▽⌒)
welcome hope you find some you like. I'm not so into heavy yaoi so most are kinda light, don't know a lot of heavier stuff....so keep that in mind.
check out nanu-nana`s blackmail list
http://www.mangago.me/home/mangalist/46288/
yaoi where the seme first bullies or threats the uke?