Batman

Batman is the main protagonist of the film and the hero of Gotham City.

The Lego Movie
Batman is one of the main characters in The LEGO Movie. He saves Emmet, Vitruvius, and Wyldstyle in the old west. He accompanies them on their mission to bring down Lord Business. As time wears on, Lucy begins to fall for Emmet which Batman notices, but doesn't mind. In the end, he gives his blessing for her to be with the hero she deserved.

The Lego Batman Movie
Batman is back in Gotham, dealing with his Rogue Gallery. Along the way, he meets Batgirl and Robin who become a part of his family, along with Alfred. Though it takes him a while to open up and accept them as family due to fear of losing more people he cared for.

The Lego Movie 2: The Second Part
Batman is back in Bricksburg, now Apocalypsberg after his "solo adventure." However, Sweet Mayhem kidnaps him, Metalbeard, Unikitty, Lucy, and Benny to take them to the Systar System. There, Queen Watevra Wa’Nabi plans to wed Batman to unite their worlds, believing him to be the leader. Batman is very off-put by the idea of marriage but agrees to the wedding to outdo Superman when Queen Watevra Wa’Nabi claimed he was her first choice.

Personality
Batman is often seen at the surface level, criticized for his lack of care for other's well-being. After the death of his biological parents, Bruce himself had grown far apart from others and strives to protect himself from losing any loved ones again, leaving him very lonely as a result. Especially before his change in The LEGO Batman Movie, he attempted to cover his insecurities with snarky humor or childish disobedience (much to the dismay of Alfred). After days of action and excitement, while the whole city would celebrate Batman's heroic actions, he found that hiding within the depths of his manor would ease his mind away from the stress of risking those he loved.

He finds his truest form of companionship when he meets Queen Watevra Wa-Nabi, whom he was arranged to marry to reunite his world with her's in peace. He wasn't interested at first, but his ego gets the better of him when she sings about preferring Superman. Afterwards, he proposes to her to prove that he's better. Despite a non-altruistic start, he comes to feel a connection with her when he hears how she was also lonely living in a palace with only a fussy British servant and nobody to relate to her. With her influence, he becomes a more cheerful person and happily marries her in the end, successfully uniting their worlds.