I have an immortal character who’s a thousand years old and is not afraid to get close to people. In her early years as a human she went through a lot of loss and pain. Over the years she’s realised that relationships with others are precious even if they may be cut short so she treasures every moment. Has this idea been lots of times? I don’t want to write an character who’s a hermit and cut off interaction completel
I honestly haven’t read every book ever published, so I can’t say whether or not this idea has been done a lot of times. I mean, I think the classic interpretation of an immortal was usually the cold/cut off/hermit type of person, but the modern interpretation trends more along the lines of the Cullens, the Salvatores, the Mikaelsons, etc., where they are more open to relationships and friendships.
In any case, even if it has been done before, I don’t think that’s any reason you can’t do it. It’s not the type of thing that would count as a cliche. :)