How could you NOT love Meliodas? Sure, he can be a bit moody and pessimistic at times, but that just means he’s one of the only people who calls it like it is (particularly when it comes to Elizabeth), not afraid to say what everyone else is thinking, even if they’re all fawning over her (much to her chagrin). Not to mention Meliodas has been shown to be incredibly caring towards his comrades and the princess, putting himself in harm’s way when someone dear to him was in danger.
The Old Personality:
With his old personality in control, Meliodas has been seen to be easily annoyed and angered, being far more brutal, sarcastic, sadistic, and cruel than ever. He does not care about other people’s lives at all, even going as far as threatening to kill Ban simply because he was standing in his way. Despite his killing intent towards Ban, however,
The Meliodas still accept him back into the team after regaining his memories. His speech pattern when talking normally has also changed drastically: while he used to speak with a very polite tone of voice before (he only cursed under extreme circumstances), when reintroduced by Gowther during their first appearance in Camelot, he already had a rather casual manner of speaking; no longer using honorifics or desu endings.
When he first re-meets with Ban and King, he shows some discontentment due to how Ban has grown over his absence. Meliodas also tells Ban how Gowther’s reason for sealing him was pathetic and that he should be grateful towards him for saving his life by sealing him away.
During his encounter with Hendrickson, when he attempted to take control of Meliodas’ body after revealing himself as a member of the Ten Commandments and calling him a nuisance, Meliodas remained calm and accepted his fate; even going as far as requesting Hendrickson to kill him since he no longer had any memories or emotions within him, effectively dying in peace.
The New Personality:
When he was alive, Meliodas was calm and loyal person who had a code of honor to protect people in need. He also cares deeply for his comrades and will go to great lengths to save them. Meliodas has a laid-back personality, as he is rarely seen being serious except during battle or when someone close to him is harmed. His carefree attitude often annoys others but also gives him charm and charisma that attracts some people to him. When meeting Elizabeth, his usual perverted nature sometimes leads him into childish disputes with her, despite their mutual respect for each other; she even goes so far as to call him an old man on occasion because of it.
Despite his perverted tendencies, he has a great sense of honor and pride. He becomes furious when people insult him or Meliodas calls him out for being weak. He despises having to work with Elizabeth at first, but after seeing her determination to save him and her skills in battle, he respects her as an equal, though there are moments where his usual personality shows through in front of others. Even after regaining his original personality, he continues acting friendly towards Elizabeth, who returns the gesture by treating him with respect and keeping the friendship that they developed while fighting to save Camelot.
One thing we all know about Meliodas’s old personality is that he was a sadist. He relished in making other people suffer—not just because it made him stronger, but also because he enjoyed it. He would often play with his victims’ emotions and kill them off before they could actually get out what they were trying to say (something he never did to Elizabeth). Though she’s proven to be slightly dumber than usual, Ban has picked up Meliodas’s cruel streak perfectly.
But while his old personality was a sadist, it was only one of many traits he had. He had a sense of loyalty to his friends and allies, and if they were killed or hurt by his hand he genuinely felt remorse over it—with some truly heartbreaking moments being brought on in particular because of it.
And though you’d be correct in assuming that Light Yagami still feels pangs of guilt for these actions, despite not remembering anything about them now, Ban’s cruelty has been shown to vastly outweigh any kindhearted side. There are countless instances where he relishes in people’s fear as he approaches them and taunts them with threats of what will happen if they don’t listen to him.