Thanatos is a very talented warrior, physically and emotionally. He's very discipline and very protective of the Egonizers. He's immortal though, he thought it as a curse more than a blessing. The egonizers are an evil organization with good intentions but won't hold back for anything, if they have to sacrifice a life,so be it
Thanatos is also very respectful and considerate about topic mentioning death, he's fascinated by the concept of death itself but respect it none the less. He's a human.