Mine's simple Bertho (I pronounce yours in my head with a T sound as I've gone Frenchie I guess!), it's just literally the Heather plant or flower. It's also the name of a famous French writer who has a particle...
It's also sentimental to me, as my real names both have seven letters and that one is very close to my real name. seven letters and several of the same ones...
Feels right somehow.
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I was born under a wandering star.