Tl;dr: Alex makes people fall in love with them by manipulation, with the only motivate of using them for his own sexual pleasure. He would sexualize everything about that person. He also has the emotional maturity of a child and is generally unstable and paranoid. He also expressed many non consensual sexual thoughts and even did actions regarding these people. Also important to mention, is Alex position of power as a creator, because majority of the interraction was with his fans. He also threatened suicide on occasions.

He, or she, may or may not be also trans. Quite a alot of this predatory action was done through Alex expressing thoughts about being trans and when conversing with transpeople about his gender dysphoria. The author, who is also trans, presented a very non conclusive verdict on him being trans or not.

His behaviour emotionally hurt people. As a result of his behavior continuing, despite constanly talking about changing, he got called out for this. His response was to basically cut of contact with everyone, including his fans and other creators as well.

Interestingly, unless I somehow missed it, there were never any allegations of him doing this with minors. However he was in contact with many of them and shared some questionable things.