Grandpa is inside a glass cage, his hands and feet restrained by rusty shackles. He has a long white beard, which hangs down to his chest and frames his face, attesting to his advanced age. His clothing is well-worn, a dirty and tattered blue robe that hangs loosely off his body. His eyes appear tired and sad, surrounded by wrinkles that tell the story of his life. He looks weak and frail, as if the slightest touch could break him into pieces.
To bring the illustration to life, use colors to express emotion and mood. Use a gentle yellow for Grandpa's robe, as if it holds a hint of warmth and comfort. The glass cage could be a deep green, symbolizing the harsh captivity it holds. The shackles could be a dull brown, highlighting the oppression and restriction that Grandpa is feeling. Finally, a soft blue could be used for Grandpa's eyes and beard to represent the sadness he exudes.