Liam's Rockruff is one of Liam's Pokémon that he caught prior to the series.
Prior to the series
Not much is known about Rockruff. All Liam really reveals that he caught Rockruff during a family vacation in the Alola region.
Rockruff makes her debut in the second half of Kanto 3: A Rocky Battle. Liam's uncle Forrest is set to battle Aeryn McKnight but he suddenly falls ill resulting in Liam taking over
Personality and characteristics
Rockruff is a playful, affectionate Pokémon, and is fiercely loyal to Liam. She has a personality switch at times, stated by Liam. She has a friendly and calm mode and a fierce and protective mode where she becomes serious. Despite having two personalities, Rockruff is still the kind, friendly and affectionate Pokémon Liam's always had.
Like other members of her species, Rockruff likes to greet and show affection to others by rubbing up against them with the rocks on its neck, although she doesn't seem to be aware that it stings the recipient.