Description has to state explicitly what to do with names with multiple occurences of common letters.
Take the following example:

show_relationship('KEVIN', 'ANN') == "Enemies"
KEVIN and ANN have character `N` in common.
You must cross out all Ns in both names: 1 in KEVI~N~ and 2 in A~NN~.
After this step, only 5 letters remain.

I think there's a problem with the randomized test. Cause it says on the log:
HSREBQTK
FLLCG
13
1
We get the value 1 which obviously corresponds to "Friendship" but an error occurs and says:
expected:<[Siblings]> but was:<[Friendship]>
although on previous randomized test with the same result:
KRK
BOOZJDTZVI
13
1
There is no error
Please fix this.