Being old doesn't mean she'll just be old and grumpy. Hell, in Midnight Suns she's not grumpy at all. I don't think she's that in general. She's more the wisened guide. She also has a great sense of humor sometimes. All any character takes is a good writer.
Now me, I'm just old and grumpy, and play WoW. I'm not fleshed out at all. Others my age are more well rounded, lol.