"Mawile's huge jaws are actually steel horns that have been transformed. Don't be taken in by this Pokémon's cute face — it's very dangerous and can lull its foe into letting down its guard. When the foe least expects it, Mawile chomps it with its gaping jaws."
"When Mawile undergoes Mega Evolution, its trademark huge mouth has multiplied, and now there are two great maws to contend with. t even seems that Mega Mawile is able to control each maw independently."
Mawile first appeared in A Deceiving Interaction!, when Lexi and her friends traversed through Granite Cave. While there, they were attacked by Mawile, who was in chains. After using her Houndoom to create light, Lexi stopped the Mawile from attacking them, before releasing her from the chains. Using Ralts, she discovered that Mawile was captured by a traveler who clapped her in chains and left her. Feeling empathetic and also impressed, Lexi decided to capture Mawile, who also showed much strength and fine technique. Despite its initial rejection of being captured, its weakened state led it to be captured, seemingly unhappily.
From this point on, Mawile continuously disobeyed Lexi throughout their journey, leading to Mawile losing battles. During Mawile's first battle with Lexi against Brawly, she refused to do as Lexi told, showing her disobedience for the first time. After first hand watching Lexi's SableyeMega Evolve, despite its lack of strength compared to her, Mawile decided to make an effort with Lexi, and soon found herself liking her. As Mawile began to trust and like Lexi more, she began to show much improvement during her battles. It was at this point Lexi atempted to Mega Evolve Mawile, however, they were unsuccessful in doing so. It was long after this that Mawile proved it loved Lexi by protecting her when attacked by Team Aqua, in which Lexi then attempted to Mega Evolve Mawile, in which she did so for the first time. Mawile became one of Lexi's strongest and most loyal Pokémon following this.
When first caught, Mawile was a stubborn and smug Pokémon, who refused to be at all cooperative with Lexi. As time passed, she showed more of her true personality which was that of a loyal and understanding Pokémon. Despite her true nature, she's also shown to be quite feisty and angry, especially when battling those it dislikes.
Mawile is able to use her docile-looking face to lull people into complacency, then bits with her huge, relentless jaws. These are actually steel horns that have been transformed, that can bite through iron beams.