I think in this sentence, the key is "always". Consider these:
(1) Aunt Lucy turned up without warning and brought us a present
(2) Aunt Lucy would turn up without warning and bring us a present
(3) ?Aunt Lucy was turning up without warning and bringing us a present
(3) here is the most similar to the original, just dropping "always". However, this is a weird sentence (note the ?), and it would be used in limited contexts, such as interjections during story telling or as an answer to a question. It doesn't have the repetition meaning.
(1), in the past tense, does not have a repetition meaning.
(2) does has a repetition meaning, and it doesn't have "always" -- rather, the use of would in this construction (X would VERB and DO Y) is bringing in the repetition meaning. Note, though, that "always" very naturally fits in to this construction.
John would (always) make the best cookies
Sally would (always) go to the baseball game
"Always" and "would" are often used similarly in this sort of construction to mean essentially the same thing.
In terms of specifying emotion, these sorts of "always" and "would" statements are usually associated with positive emotions or happy memories, but are sometimes also used in negative contexts, but much less often, and usually with emphasis on "would" or "always": (emphasis denoted with *'s)
Joe *always* left his clothes all over
Mary *would* not show up to the concert
However, much of the time, a negative sentiment expressed in such a construction actually makes the construction positive, such as:
Bill would always leave the lights on
This sort of construction is often associated with longing for this behavior, good or bad.
Note also, as might be expected with a past tense expression, this sort of repetition meaning entails that the action is no longer repeated. The end of repetition in this context is usually associated with no longer spending time with this person, most commonly because the person has passed away. Compare with:
John makes the best cookies.
Which does have a repetition meaning as well (and no meaning about the person having passed away).