I'm not sure about specifically good ones. Fanfiction in such a niche and often inappropriate combination might be hard to find in mainstream platforms due to its rather odd and potentially violating nature of normal ethical and content guidelines.
One possible plot could be a story of a human who discovers a stranded xenomorph and, against all odds, forms an emotional bond with it that develops into a romantic relationship. They might face challenges from their respective species, like the human facing rejection from his own kind for loving an alien.
There may not be mainstream well - known ones in the general sense. However, within certain niche fanfiction communities, there could be some popular works. But they are often not widely publicized due to the rather unusual and specific nature of the pairing.
A Xenomorph might be friendly if it formed a symbiotic relationship. For example, if it realized that by working with other species, it could get more food or better living conditions. Say there was a planet where the Xenomorphs and another species both needed a certain resource. Through cooperation, they could both thrive, and the Xenomorphs could become friendly towards the other species over time.
A friendly Xenomorph might have less menacing features. Instead of its usual sharp, menacing claws, they could be shorter and less pointed. Its body color could be more muted, not the typical dark and intimidating color. Maybe it would have a more rounded shape rather than the angular, scary form it usually has.
The concept seems highly inappropriate. The xenomorph is not a typical character for romantic or sexual relationships with humans in the first place. And when adding the 'gay' and 'lemon' aspects, it goes against the general moral and ethical boundaries of most fanfiction. Fanfiction usually focuses on more relatable and acceptable relationships based on the original works, rather than this kind of out - there and often offensive combination.
You could write about a group of survivors trying to outwit a Xenomorph in a derelict spaceship. It would be full of suspense as they use their wits and limited resources to avoid being caught.
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.
It could start with fear and curiosity. The human is initially terrified of the xenomorph but as they observe it, they notice some unique behaviors. This piques their curiosity and they start to approach it cautiously.