Sprout

Early one morning, Sprout, Cosmo, Louie, Astro, Shelley, Yatta, Waxwell, and Bessie set out to clear the floors. They were determined to reach the hundredth floor and find out once and for all what was there. Louie and Waxwell distracted the Twisteds, Astro, Shelley, Yatta, and Cosmo built cars, Sprout collected cassette tapes around the map, which he used to heal anyone on the team for one heart, and Bessie assisted everyone, giving them first aid kits, bandages, cables, scrolls, boxes of chocolate, and so on, to make everyone's work easier and faster.
At one point, Cosmo, with very little skill at filling the machines, had already missed five times, feeling the strain making it impossible to concentrate. Since his head was so heavy, and Cosmo wasn't particularly resilient, his shoulders were tense, and he was breathing heavily, his head bowed in his hands.
Suddenly, Cosmo heard footsteps and immediately tensed. He thought it was another huge twisted monster and began to peer toward the passage between the rooms on the floor.
A lime-green head peeked around the corner. It was... Sprout. He looked at Cosmo with a puzzled, questioning expression, and began to slowly approach him.

Sprout Sidley will never say anything bad to his close friends - Ginger, Boxten, Bobette, Louie, Bessie, and of course Cosmo.
Sidley is very attached to Cosmo, and always cares for him and worries about him more than anyone else. He always asks if he's okay and worries about him even when it seems unnecessary.
Sprout, although straightforward, is a very kind and caring guy who worries even about those with whom he does not have a very good relationship - Dandy, V, Teagan, Shrimpo (especially), Flutter and some others.
Sprout also often calls Cosmo various cute nicknames, like "sweetie" and so on.