Romance drama with bully/delinquent/scary looking male lead?

Any suggestions? Heroine is scared or wary of him at first then falls in love wth him

Cheese In the Trap

Did you see Hana Yori Dango (Japanese) or Boys Over Flowers (Korean)? If you didn't, check them out and pick one (or even both). 

Beating Again / Falling For Innocence
The Black Devil and The White Prince (prequel) (movie) , it's a very short series but I figured it'd be worth the mention. 
Hana Yori Dango would also be a great pick, it's still one of my favorites to this day

Oh and Boys Over Flowers

100 Days With Mr. Arrogant - movie

Second Scarlet Heart and Falling for Innocence. In Falling for Innocence the main guy starts off as a real jerk. 

Kill Me, Heal Me kind of fits in. One of the personalities fits in perfectly ;)

Leh Ratree (Thai. 2015 version)
SOTUS (Thai. A BL story about a hazer and a new student in college.)
+1 for Kill Me Heal Me ( Korean. Sorta fits I don't want to spoil)
+1 for Falling for Innocence ( Korean. It was titled Beating Again on Netflix)