Role of 'that' in this sentence? [migrated]

I am recently reading an English book to improve my English skills.

In the book I am now reading, there is a sentence,

There is nothing Hypnos and Morepheus can do to soothe your aching body, to calm your racing mind, to ease your wounded spirit, that I cannot match with something sweet and warm of my own.

I cannot figure out what the role of bolded "that" in this sentence is. I believe it is a conjunction but don't know what the exact function it is doing in this sentence.

Solution 1:

There is nothing Hypnos and Morepheus can do to soothe your aching body, to calm your racing mind, to ease your wounded spirit, that I cannot match with something sweet and warm of my own.

Yes, it's a conjunction, more specifically a 'subordinator'. Its function is that of 'marker', i.e. it marks the clause that I cannot match with something sweet and warm of my own as being subordinate.

This is called a 'stacked' relative construction, one where a defining relative clause combines with its antecedent to form a larger unit which is antecedent for a second defining relative clause.

In this case, Hypnos and Morepheus can do to soothe your aching body, to calm your racing mind, to ease your wounded spirit combines with its antecedent "nothing" to give nothing Hypnos and Morepheus can do to soothe your aching body, to calm your racing mind, to ease your wounded spirit and this is then the antecedent for the second relative clause that I cannot match with something sweet and warm of my own.

This kind of recursion is known as 'stacking'.