Antyvul is a very friendly and kind pichu. He takes pride in helping others in any way he can, and quick to provide assistance when asked. However, he is also very sensitive to negative emotions, such as anger. He can easily be scared away and will avoid people if a large amount of negative emotions are directed towards him. The type of emotion will also change how he reacts. For example, anger and rage will chase him away, while sadness will make him quietly remain nearby. The happiness of others helps fuel his own happiness. This strive for happiness is what helps push him to assist others. While he means well, this can easily be exploited.

Antyvul has always had a very outgoing personality, happy to make new friends and talk to complete strangers. While growing up, he would constantly try to gather things and collect stuff he thought would come in handy to help out in some way. The young chu took joy in helping others, feeling a sense of worth in accomplishing something of value to someone. Though he does gain a sense of happiness and satisfaction from this, it has never been enough to reach a level to evolve to a pikachu, as there is always someone else to help.

Without Limits

While Antyvul does have a sense of right and wrong, the desire to be helpful to others can have severe disadvantages. For example, he does not seem to know limits very well and can easily be taken advantage of with multiple favors being asked in succession. It is very difficult for him to say no and break the cycle, though he does try to limit it to 5 favors per person. Despite his leaning towards good alignment, he can be tricked into doing evil deeds if presented to him correctly. When Alterchu came to Cienel to eliminate Antyvul, he took notice of this potential. Rather than kill him, Alterchu chose to train Antyvul how to use some of their Life Force abilities to have an ally in an emergency situation. This has given Antyvul the ability to slow time, immense strength, and rapid healing. He is not as strong as Alterchu in these abilities.

Survival

His personality and method of battle have resulted in a unique method of survival. In terms of battle, he is generally a pacifist. His two main attacks are not really attacks at all. Thunder Wave causes paralysis, allowing him to make an escape. Tickle is intended to drop his opponent's guard to again make for a getaway. In a worst case scenario, Endure is used in combination with Flail. Endure promises survival of an attack with at least a shred of health, while Flail does immense damage at dire levels. His personality to help others has been found to be very valuable, even to those of evil intent. Local criminal organizations have found him to be useful. While he is not a member of any, they see him as an asset. Without his knowledge, he usually has a bodyguard or two secretly following him from the shadows to keep him safe.

The Truth?

Rumors have begun to circulate about the true relationship between Alterchu and Antyvul. As a result of these two being the only alternate dimension versions that look identical, it is speculated that Alterchu is really Antyvul’s father rather than alternate dimensional version. Alterchu had mentioned a plot previously to make his son as powerful as himself, but Antyvul is actually more powerful. If this were true, Alterchu wouldn't want people to know about his son as it causes an exploitative situation. It could be theorized that if the son was kept sheltered in a very protective place, it could cause a situation like Antyvul who likes to be around others, but very shy about talking. None of this has been confirmed and both seem to deny it.

Due to the stigma of being a pichu, along with his very childlike personality and antics, Antyvul is always assumed to be a child. With that presumption, no one has actually even flirted with Antyvul since they treat him as a minor. While he is fully mature and capable of doing adult things, he hasn't shown any interesting in anyone either. Though he has gotten blushy and nervous around individuals he found cute, he's never gone beyond that to express such feelings to someone. It's possible that his shyness is preventing him from conveying any sort of affection. For these reasons, his sexuality is not known at this time.

While Pokemon states pichu and others are "baby" pokemon and cannot breed, Pokemon has also demonstrated several times that evolution is not an indicator of age/maturity. As a result of this, I believe any species of pokemon are capable of reaching "maturity" through normal growing of age. Evolving dramatically speeds up this process as they morph into their new form. So a riolu, for example, can reach "maturity" either by naturally aging with time or immediately by evolving into lucario.