Final answer:
There is no information about Nic or Caela in the provided text excerpts, therefore an answer to the question about a mark on Nic's shoulder caused by Caela cannot be given based on the given references.
Step-by-step explanation:
The question pertains to a specific detail within a narrative, which likely comes from a piece of literature. Unfortunately, the given text excerpts do not provide clear information about 'Nic' or a 'scratch on his shoulder' from 'Caela'.
However, there are multiple references to a mark or blemish in these excerpts. For example, the text includes a passage discussing Georgiana's mark on her cheek, which her husband Aylmer finds objectionable and wishes to remove. This narrative element seems to parallel the student's question about a mark, although the characters and circumstances differ.
There is no mention of Nic or Caela or a scratch in any of the provided text excerpts, so based on the provided information, we cannot accurately answer the question regarding the mark on Nic's shoulder caused by Caela. It's possible that this question refers to another story or book not included within the given text references.