Describe a character named Alex who is a mysterious and enigmatic individual with a hidden past

Describe a character named Alex who is a mysterious and enigmatic individual with a hidden past. They are always seen wearing sunglasses and often disappear without warning, leaving others wondering about their true intentions. Despite their enigmatic nature, Alex is charming and charismatic, capable of quickly gaining the trust and admiration of those around them. However, their secretive nature and occasional cryptic remarks make it difficult for others to truly understand who Alex really is.