The novelty. It's not often you think about two such different and fearsome alien species being in love. It's like mixing two completely different elements that you wouldn't expect to go together, like fire and ice.
There's also 'Love Beyond Species' which not only focuses on the relationship between a xenomorph and a predator but also the reactions of their respective species. It's quite interesting as it shows the challenges they face while trying to be together, like cultural differences within their alien races.
Skull could be an original character created for this fan fiction. He might be a powerful ninja from a far - off land with unique skills and knowledge.
Another great one is 'Alien: Sea of Sorrows'. It delves deeper into the xenomorph lore and the universe they inhabit. It has a complex plot that involves different groups of people trying to deal with the xenomorph threat in a unique setting. The descriptions of the xenomorphs are vivid and terrifying.
It's hard to give a precise number. Xenomorph comics have been produced by multiple companies over the years, and new ones may still be coming out. You could check with comic bookstores or online comic platforms for the latest information.
Predator and Alien were classic sci-fi novels as follows:
1 Predator (Warrior Series): Written by William gibson, it includes Predator, Alien: Contract, and Alien: Origins.
2 Alien (Alien series): Written by Ridley Scott, it includes Alien, Alien 2, and Alien 3.
I hope you like these novels.