The affection Ripley shows towards Jones (image above) in the first two movies, despite being in almost constant danger. In particular, running back to rescue Jones from the soon to be exploding ship, despite the fact that she knew it would put her in the path of the xenomorph.
A brief moment from the first film has everyone crowding around Kane cheerfully after he wakes up.
Parker and Brett's friendship. While most of the crew has trouble getting along, the two of them are shown to enjoy each other's company.
When Ripley is startled by the corpse of the Facehugger, Dallas immediately jumps in front of her and shields her with his body.
Similar to the above example, when the chestburster emerges from Kane's body, Parker instinctively jumps back and puts himself in front of Ripley, shielding her. Even more heartwarming, this was most likely the actor's genuine reaction to witnessing the horrifying effect, and him instinctively protecting Sigourney Weaver.
Parker tries to tackle the Alien to save Lambert, and his last words are telling her to escape from the room. Sadly, it ends up being a Senseless Sacrifice.
In a deleted scene, Ripley reassures Lambert that she'll do her best to get all of them out alive.
