The real Alcor perceived the girls in the Arcturus Forest and alerted Ursula of that fact.
Akko is introduced to Alcor when she visits Ursula's room to inquire about her "past" with Chariot. Akko does not know that Ursula's familiar is named Alcor, like her plush toy of Chariot's familiar. Akko does comment that it's the same species as Alcor but doesn't realize that that he actually is him.
Alcor was called by Ursula to bring the Shiny Rod back to Akko. Ursula can also project her voice through Alcor because he is her frimilar.
Alcor is a loyal familiar to Ursula. She can call him to assist her by whistling. Alcor also informs her about strange events that he perceives. Ursula can also project her voice through Alcor, although Alcor can not project his voice through her.
Akko has a plush toy version of Alcor, and it's one of her most beloved possessions. Akko first met Alcor in Blue Moon and it seems the latter has a particular liking towards the former. Akko knows that Alcor is the same species at Chariots frimliar and looks the same, but doesn't connect the dots.
- The plush version of Alcor looks exactly the same as the real Alcor, exept it's fatter and tinyer.