User blog comment:Hiccup Haddock III/Ask Me Anything!/@comment-26523574-20150804033752/@comment-25800883-20150804040717

maybe they will find female Night Fury that shows high aggressive personality to other dragons possible she might not try to interact with Toothless.

She might show to push him away possible being alone for years shows her high independent and anti-social behavior but HIccup might help out but she might attack him and Toothless fights her off

It may be like Lion King how Sumba and Nala. all over again as they will try to play with each other and Toothless might not interact with Hiccup for while.