Tully is not the best with names but he picks up on physical details and other things more than the average rabbit. Stacy is defined in his eyes by her cute and expressive eyes, adorable little buckteeth, and fluffy golden hair. If anything about her changes too much, it's just not Stacy anymore. As much as he loves to spend a whole afternoon in bed with her, stopping to give her a good brushing or shower is just as important. Stacy does not know the real context to his affections but she loves it all the same, to her it's just her big brother being nice and giving her a break between rounds. Funny how that works out.
