Gilbert is that guy.
The hopelessly devoted one whose loyal affection often ends up disregarded by those he cherishes.
The one who pushes his own fears and pains and worries to the side in order to help others.
The one whose smile is always a little bit sad.
The one who fears being left behind.
And the one who, in spite of whatever he may be feeling at any given moment, is always needed by everyone.
And that's why he's my favorite.
In Pandora Hearts, Gilbert functions as one of the series' main protagonists. Adopted by the Nightray family, Gilbert is the close friend and loyal servant of Oz Vessalius. While Oz is trapped in the Abyss, Gilbert learns to command the dangerous chain Raven and also joins the Pandora organization under the guidance of one whimsical Xerxes Break.
Gilbert can be characterized best by his relationships, and almost all of those are vexed. Oz, his best friend and the center of his universe, has his own set of problems, and so Gilbert often ends up pushed aside and sometimes ignored in favor of the Chain Alice or more pressing matters. His mentor Break has a bad habit of teasing him and forcing Gilbert to confront questions he doesn't really want to answer. And even those who do adore Gilbert cause him no end of problems; his brother Vincent takes a delightfully amoral approach to their relationship, willing to destroy anything and anyone that he imagines might interfere with Gilbert's happiness.
Both powerful and powerless, Gilbert is a walking contradiction with so many burdens to bear it's nearly unimaginable. He commands the Chain Raven and ultimately realizes he's one of the powerful Baskervilles, but his deep devotion to Oz and his willingness to push his own needs aside often means that he rarely has a voice or a say in the events that occur. In some ways, the deranged Vincent acts as an advocate for Gilbert since Gilbert himself often lacks agency.
But Gil's sweetness, his loyalty, his endless love defines his character in a powerfully profound way. When he loses his master to the Abyss, he first breaks down and then devotes himself to the ten-year task of waiting for and reclaiming Oz, then returns happily to his role as a servant. He protects and fights for Xerxes Break, fulfilling his promise to serve in place of Break's missing "left eye." And he even learns to fight alongside and for Alice, the very Chain whose presence demands his master's attention and causes him so much trouble.
As the manga progresses, it becomes evident that Gil needs to confront, and will have to confront, himself and the relationships around him. His unquestioning loyalty and his strong sense of self-sacrifice--long questioned by Break--hides a painful past; the discovery of his own identity and nature accompanies a powerful sense of loss. What Gilbert might choose to do or be when he acts fully and consistently of his own volition, and not as a servant, is anyone's guess, but given the sweetness of his character and the childlike depth of his love for those around him, I'd say it will be something amazing.
In many ways, Gilbert has grown with Pandora Hearts, and--despite the inherent tragedy and pathos of his character, the little servant boy always reaching out for affection--his narrative is one of the most powerful and evocative in the series. I like to think it's because even though he's a man--strong and able to fight on his own, the caretaker and guardian of those he holds closest to his heart--maybe what his boyish heart needs most is a warm embrace and a return on some of that boundless affection.