half human half monster hybrid

[Herlock Sholmes]

what would happen

[Sans the Hedgehog]

Dreemurr Reborn, if soul hybrid.
Some confused monsters and humans, if legit hybrid.

[Weshek]

Chara.

[bhwgamer]

If we just assume that it's biologically possible in the first place, then a hybrid would probably just be similar to whatever Chara and Asriel became when they fused SOULs. Of course, it would be a bit weaker since it has the power of only one being.