I really liked the imagery you used in this poem, especially in the first stanza. I could really picture the scene in my head and its potentially foreboding end. Something that did throw me off a little was the change in tense in the final line of that first stanza, as the line is in past tense while the rest of the stanza is in present tense. The second stanza feels a little different than the first; the rhythm changes as do the rhymes. However, it also seems at this point that the poem is changing where it's going, so this could also be a really good choice to make. I love how you involved patronuses and kept the magic in the poetry! Overall, it's a lovely poem that conveys the effects of a patronus, or a happy thought, during a difficult time.