Cloudy typically appears as a sentient pink cloud with eyes (usually blue, sometimes green) and a mouth. When summoned while Star is channeling her magic negatively, Cloudy appears green instead of pink.
From "Club Snubbed" onwards, Cloudy's appearance is different. He is now a darker pink, with translucent purple wings on his sides. His eye color is also changed from dark teal to light indigo, with permanent blush marks on his cheeks.
In "Royal Pain", Cloudy briefly appears among Star's various monster friends when she shows King Butterfly her bedroom. He also appears near the end of the episode, serving as Star's transportation as she casts a spell to flood the house.
In "Wand to Wand", Cloudy appears green instead of his usual pink when Star channels negative emotions while casting Summoning Cloudy Charm. While in this state, Cloudy is sluggish and carefree, creating a big mess around the Diaz Household and not caring. When Star tries to zap him back to normal, he gets mad and grows into a furious storm cloud, impervious to many of Star's magic spells. It is only when Star channels her positive emotions again that her magic finally turns him back to normal.
In "Club Snubbed", Star conjures up Cloudy to help her confront Tom. In "Stranger Danger", Star uses him as part of her plan to regain her wand. In "Starfari", Cloudy appears as Star helps the monsters save their village. In "Ponymonium", Star flies on Cloudy to and from the Cloud Kingdom of the Pony Heads. In "Holiday Spellcial", Cloudy is seen within Star's wand, attending the spells' Stump Day office party.
In "The Bogbeast of Boggabah", after Star grows frustrated by her father insisting they sit in a sauna for a long time, she summons Cloudy to flood the tent.
In "Butterfly Follies", Cloudy carries Star, Marco and River's luggage while they search for Queen Moon.
In "Escape from the Pie Folk", Star, Marco and River take Cloudy into the volcano where Queen Moon is discovered baking, and later ride him out, although he goes green and gets sick from Foolduke's monkey feeding him too many pies.
In "Lake House Fever", Star uses Cloudy like a surfboard while surfing in the Underworld.
On most occasions, Cloudy appears bright and smiling, happy to help Star in any way he can. When influenced by Star's negative magic, however, Cloudy is lethargic, carefree, and somewhat passive-aggressive. He cares little about the consequences of his actions or about Star's wishes, and is easily driven to anger.
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