Heine Wittgenstein is one of the Angels from the Overworld, and teacher to Aladdin back in Synapse. He is praised as the brightest mind in all of Synapse, and believed to have been the teacher to Celestia.
Though Heine is a grown man, he's often mistaken for a child due to his short stature. He has dark red hair and amber eyes, and wears glasses. He wears a black cap with white lining at the bottom and a white tassel.
Heine rarely shows any type of emotion and is incredibly stoic. He acts polite towards everyone at all times, even when insulting them. He seems harsh and cold, but is actually very empathetic and understanding of people. He's intelligent, but does not flaunt it. The only times he loses his composure is when someone mistakes him for a child.
Prior to the series, Heine Wittgenstein was one of the teachers in Synapse, being the mentor to Celestia, and then later on, Aladdin. His behavior is hinted at him being harsher than he current is, as such making Aladdin scared of him. When Aladdin ran from him in worry of his reactions to Hoopa's escape, he began to realize his behavior was not acceptable for a teacher, as they're supposed to nourish hope, not harm the heart.
Overtime, he managed to reach the Surface World, arriving by pidgeot to the front of the Orora High School on request by Celestia herself. On his arrival, he met with Gakuho Asano, in hopes he would become one of the teachers for the school. He was given a written test to check his intelligence, which he passed fairly easily. He was accepted in, and given the day to learn more on the school, and better understand his surroundings. He took the time to understand the "ant" system, and overtime he disapproved the matter, to the point in moving the E class from the 3-E Bulding to the main building against Gakuho's wishes.
As a teacher of Orora high, he also introduced Ciel Phantomhive, Edward Elric and Alphonse Elric into class 3-E outside of Gakuho's knowledge. After the school day ended, he found Team Harmony at the E building training when he heard word of Aladdin's presence. He eventually managed to find him with the team, and he admitted it was more his fault that Aladdin ran away, and he was more worried over Aladdin than Hoopa, making amends with his student. He also was the one responsible for the field trip to Elysium, originally in hopes that they would not only learn more about Angels, but also in hopes of fixing Edward's broken automail. On the field trip, he also kept up with testing, given a heads-up by Nagisa Shiota.
Upon returning, he was called to Gakuho's office for another competence test, one personalized and highly advanced by Gakuho himself. Not only did he complete it, but he also pointed out flaws for Gakuho, finally making him snap. Team Harmony met with him the next morning and had him under their guard to be sure he didn't get hurt, as it was foretold he would get killed by Gakuho. His fate was changed however after Ciel's involvement, and as such he survived.
After the ordeal, Heine went to work on finding the location of the missing Djinn. When he did figure it out, he got a message out to Aladdin, and explained to him on the task at hand. He was ready to head off, but after some explaining on Aladdin's part, Heine allowed him to stay a while more before leaving to say his goodbyes.
Once ready, Heine and Aladdin went off to the middle east, though him insisting on the way for Aladdin to rest for a while before reaching there. When getting there, he and Aladdin started to ask around town for some clue to the location of Hoopa (even visiting a club to do so) but not leading much of anywhere. On the night they arrived, Heine discovered Aladdin's disappearance, and he went out to search for him again. As he was, he ran into Grell Sutcliff, and in the end allowed him to look for him, though only because he couldn't stop him if he wanted to. He found Aladdin next morning in company of Morgiana, and after a short confrontation, managed to recapture Hoopa.
On the capture, he and his group began to head off back to japan, stopping at Central along the way on both request by Aladdin and warning by Hoopa. The warnings were proven correct when he found King Bradley arriving. Once the king arrived, Heine challenged him to a one-on-one duel, telling the others to not interfere with the fight. He at first did well until Grell got involved, almost getting him killed if not for Morgiana's following arrival.
As they continued east, Heine and the others soon came across Gaara at his forest shrine. After their first encounter, Heine decided that night to visit Gaara personally in order to talk to him about his problems. Heine ended up in another fight, and only until after he subdued Gaara did things calm down. He got him to admit Shukaku was controlling him, but when asked how he defeated Gaara, he stated that it was something he sworn to secrecy. When Gaara explained his involvement with Shukaku, Heine questioned if running away made his heart feel any lighter, and explained to him that running away was what Shukaku wanted him to do.
After dealing with Shukaku, Heine began to head off overseas with the group, bringing Gaara with them. During the flight though, he ended up losing Aladdin and Hoopa to Sombra, and tracked them to the island where Lugia was hiding on. When Lugia fled the island, Heine decided to send the rest home as he went off after Lugia himself.
He successfully returned with him just before the final battle.