Maester Aemon calling Aerys for "My brother's poor grandson" in AGOT is based as fuck.
Like Aemon definitely has heard about all the horrid shit Aerys has done, but he's also been penpals with Rhaegar, who might have had a slightly more sympathetic view on his dad than most, and no one can tell me Aegon didn't write with his big brother! Like Egg's probably been telling about how sweet little Aerys lost his first tooth, drew dragons on the wall or got into trouble with Steffon and Tywin.
So for Aemon, Aerys first and foremost isn’t the Mad King, he’s Egg’s troubled grandbaby.