Sullivan

Personality:

Sullivan's personality can be put into two distinct parts: the one he wants you to see, and the one that he does not. 

To strangers, he's sassy, a little haughty, and confident. He wants you to see him as someone competent -- not necessarily in a 'better than you' sort of aspect, but simply someone impossible to converse with more than idle conversations. However, once you get past his one inch meter of sass and prickles -- and it doesn't take much -- one will learn that Sullivan is actually very, very lonely.

Being tasked to find out how to reverse the curse he put on a whole city, as well as find a way to make himself human again, he has an immeasurably large burden that he feels that he, and only he, can perform. He keeps strangers far and those trying to be friends farther, and is terrified when someone -- Aislind  -- manages to close the distance Sully's desperately tried to keep. 

Fortunately, through Aislind's determination, and Sullivan's desire to understand his powers, he's able to confide in Aislind proper, and become more confident as a person. He proves to be kind-hearted, yet loyal to a fault -- willing to do what's best for the kingdom, and best for those he cares about, he often does reckless actions without much thought about his own well being. Post-game, his distant front softens as well, though his habits of being indirect to avoid answering proper still comes up every now and then.

Background:

Raised from a young age in the Kingdom of Cantare, Sully worked hard to keep the image that his Father wished for him to have. Practicing with his Mentor, Logan, on the daily; reading books on a wide array of topics; and ensuring that he looked his best when he'd attend political meetings with his family. But one day, on the way home, he's ambushed by demons. His bodyguards, unable to fend them off, perish -- and for Sully, a week passes without any memory.

When he does wake, however, he learns that his legs, as well as his right eye, have been cursed to become demonic. His family is unsure how to take the news, and matters become worse when his curse takes him over -- in an instant, the kingdom he called home his covered with a sea of crystalline statues.

Banished by his Father -- who's dismayed to learn that his wife was one of many encased in crystal -- Sully spends a few years on his own. He's picked up by a thief, Florine, and learns how to perform thanks to her help. But just as quick as she is to arrive, she leaves when she finds herself cornered by one of her enemies. This 'enemy' turns out to be Aislind, and together, the two find out about the true nature of Sully's 'curse' -- namely, that 'demons' are robotic in nature, and his legs are nothing more than high-tech prosthetics. He learns that his eye can be used for good (even lifting Aislind's very real curse of being unable to transform into a dragon) and eventually starts to use it to cure the rest of the Laguz who have lost the ability to transform.

By the end of the game, he's taken the throne from his father, and thanks to Aislind, his Mother has been freed from the crystals he had once placed upon her in the past. He's also finally figured out that he and Aislind have been dating for a good time now, even though the two of them have been too dense to realize it.

Abilities:

Sully, being half-demon (or more accurately, part android), has a few abilities:

• In particular, Sully's legs and eye have been replaced with more robotic ones. This makes him able to not feel anything below his thighs and, based on the temperature, can make the metal on his legs either extremely hot or cold to the touch. 
• In addition, his eye is a part of a greater whole within his head, which connects to his nervous system. Because of this, not only can other demons connect to this device to deliver one ways messages, but they can also take over either part (or all) of his body. This is the truth of his 'curse' -- and in post-game, thanks to Nahe, he doesn't have to worry about someone controlling his body without his permission anymore.
• Using his false eye, Sully can tamper with 'Essence' -- tiny, blue-colored nanobots that make up a percentage of a person's blood, and are responsible for how attuned someone is to using Magic -- forcing them to multiply on a large scale. Small adjustments allow those with poor Magic ability to use Magic at a greater potential, and can even influence Branded to become capable of transforming into the creature their Laguz parent is. However, massive adjustments force Essence out of the body, and, unsure how to adjust, solidifies into Crystal to avoid further injuries. However, Sully cannot alter Magic from fantasy sources, ie; any and all Magic from traditional Fire Emblem universes cannot be influenced by his powers. He also can't create Essence from nothing, so unless someone has any to begin with, he can't do anything to them.

Aside from the above, Sully has a few skills he picked up over the years, which includes swordplay (Rapiers in particular) and dancing, both in which he used to assist and inspire his allies. 

Other Info:

• Sully has a library back at home, where he spent a fair amount of his free time growing up reading books. In particular, his favorite are those relating to botany, and even more so flowers. 
• He likes wearing jewelry and other flashy things, but less so once he starts to travel -- by the time he meets with Aislind, he's sold most of it off, and in post-game, he favors having his attire a bit more subdued. 
• Sully's legs can be freely removed to make it easier to perform maintenance on them.