Im looking for a manga where the main protagonist is male and has a bad personality due to his past. Character development would be nice. Besides these, i dont have any other preferences as long as its not yaoi, yuri, etc.

Thankyou ^^

No yaoi, but you just described a typical yaoi character. You're missing out. So many yaoi come to mind.
Trump
Tate no Yuusha no Nariagari
I wanna say ao haru ride
Oyasumi Punpun
A Night of a Thousand Dreams
Cavalier of the Abyss
The Legendary Moonlight Sculptor
Shin Angyo Onshi
Kuroshitsuji I think Ciel is fine, but some argue
Kodomo no Omocha one of my faves
Yamato Nadeshiko Shichihenge Another fave
Horimiya Depending on what you would define a "bad" personality.

I'm missing one. I can't remember it! Ugh! Probably the most obvious too

________________
“The mind is its own place, and in itself can make a heaven of hell, a hell of heaven..”
― John Milton, Paradise Lost

So basically you're looking for a male MC that angsty because of their past? In that case you should look under the Betrayal and Trauma tags

https://www.mangaupdates.com/series.html?category=Betrayal& orderby=rating
https://www.mangaupdates.com/series.html?category=Trauma& orderby=rating

Some decent manga under them:

Berserk
Übel Blatt
Iryuu - Team Medical Dragon
Dr. Frost
Shingeki no Kyojin
Nowhere Boy



________________
Cynicism at its best.

Wow so many XD
Out of all of these, Ive seen Kuroshitsuji, The Legendary Moonlight Sculptor, Trump, Dr. Frost, Übel Blatt and Horimiya

I'll check out the ones that I havent. Finally~ I was so bored when I didnt know what to read

I laughed at this part