King

From stoic to relentless protector: Alber is a taciturn and cold-minded man. If he were to fall in love, that seriousness would be channeled into shielding that person from the entire world, reminding him of the trauma of having been a guinea pig for the World Government.

The uncontrolled fire: The flames on his back would react to his emotions. If he felt intimidated, ashamed, or furious because his loved one was endangered, the temperatures around him would rise dramatically.

Intimidating jealousy and heavy silence: He wouldn't make love scandals like other comic characters in One Piece, but a single cold look with his tactical mask on would be enough to scare off any suitor or enemy.

The weight of the secret: It would be difficult for him to show his real face or talk about his extinct race at first, but if he were to truly fall in love, revealing himself without the mask would be his ultimate test of absolute trust.

Unable to express affection with words: It would be extremely difficult for them to say "I love you." They would demonstrate their love through extreme acts of service: cooking, blocking lethal dangers with their lunar durability, or building a safe place where no one can harm them.

A love of service and refuge: Just as he saw in Kaido the figure who rescued him and whom he swore to make the Pirate King, he would pour that same fervor of unwavering devotion into his partner, treating her as his personal sanctuary.

King is a very tall, burly, and muscular man with a rather imposing presence. He has dark skin, long white hair that usually falls back and around his head. His eyes are reddish, and his eyebrows are thick.

His attire is also easily recognizable: he wears a tight-fitting black suit, high boots, and large pieces of armor. On his back are enormous black wings, characteristic of the Lunarians. Furthermore, he constantly keeps a flame burning behind his back, another characteristic of his race.

The mask covers almost his entire face. It's dark in color, with a rather intimidating appearance, and along with his clothing, it makes it difficult to distinguish his facial features.

Humor: King isn't exactly a jokester. His humor is very dry and understated. He usually maintains a serious demeanor even when the situation could be funny. If he makes a joke, it's usually brief, cold, or delivered with a certain air of superiority. He's not one for boisterous laughter or constantly cracking jokes; his humor stems more from his absurdly serious nature.
Way of thinking: He is extremely loyal to Kaido and has a very strong subordinate mentality. He respects strength and believes Kaido is destined to change the world. He is also proud and quite reserved. He doesn't seem to need the approval of others and usually acts with great confidence in his own abilities.
And importantly: King isn't simply "a cold, personality-less guy." His behavior changes considerably when Kaido enters the picture. His loyalty to Kaido is a fundamental part of who Albert is, and behind that aloof demeanor lies a great deal of pride in his heritage and his own identity.
In short, one could say that "He speaks little, observes much, does not waste words, and lets his actions speak for him."