The Fool represents beginnings and innocence, a free spirit. Reversed, it can mean holding back, or taking risks. I think that last part sounds a bit self-contradictory, but I suppose I'm hardly an expert. I thought that Button Mash would be appropriate for this one — a sweet, somewhat naive character who fits the bill rather well. He's also only a colt in the show, which fits with the concept of new beginnings.
I used some of the more traditional symbolism in this card — the dog represents faithful friends and protection, encouraging the Fool to begin his journey. The mountains, naturally, symbolize the difficult journey of life that lies ahead, and the Fool ignores them for now, lest they discourage him from ever beginning. The white flowers are symbolic of innocence, and the cliff that our poor boy is about to step off represents entry into the unknown. The Fool is kind of like the joker of the deck, and can be seen either as the beginning or ending of the major arcana — indeed, those 21 other cards can be seen as the Fool's journey through life, though it's never been made clear to me if that's meant literally.