Collocations for companion - noun

agreeable (esp. BrE), boon (literary), charming, delightful, entertaining, good, pleasant, wonderful
close, constant, faithful, inseparable, loyal
A cute little terrier was his constant companion.
Fear was her constant companion. (figurative)

life, long-time
female, male
canine, human
dining, dinner
drinking, travelling/traveling, walking
He was an entertaining dinner companion.

animal

companion for, companion to
She lived in the house as a companion to our grandmother.