In the 1d4chan summary of Changeling: The Lost, there is a line that says:
...Or, you can do the "hard but moral" thing and try to merge with it, (since, you know, it's you), which gives you even more cool stuff and merits.
However, in Autumn Nightmares, there isn't a mention of a merit received from merging with your fetch. The exact line regarding what you gain from merging with your fetch is:
When it is over, the fetch is gone and the character gains a dot of Clarity, as well as the more-valuable memories from her time in exile.
Is there a merit that represents acquiring those memories or something similar that is mentioned in another book?