Isaac was clearly granted preferential treatment throughout his life as the long-awaited son of Abraham and Sarah. Yet here we see that Ishmael's expulsion was not as final as we might have expected.
The brothers reunite to honour their father, thus showing that the two great nations Abraham fathered could still stand side by side.
Perhaps this is also an example of how death brings families back together - we don't know if it was painful or comforting, but it does seem that it was done with some degree of shared responsibility.
This is the first we have heard of Ishmael since his mother Hagar and he were saved by a well in the desert, but according to the Midrash (Pirkei D'Rabbi Eliezer), Ishmael was visited by his father, with Sarah's knowledge, after his expulsion.
Abraham is reluctant to expel Ishmael and only does so when God commands him to heed Sarah's order, so perhaps it is not surprising that the Midrash allows him to reach out to his firstborn and voice his opinion on the life and relationships he builds for himself (what else are Jewish parents for?). It allows us a glimpse into the ongoing pain that Abraham felt at this difficult separation and his attempt to build bridges.
Death often prompts difficult family conversation, and I can imagine Isaac and Ishmael had a rough time seeing to an honourable burial of their father together. Yet difficult times for us individually (and perhaps communally) can also become catalysts for healing and moments of insight into one another.
Perhaps Isaac and Ishmael's reunion can be a model for the hard work and difficult conversations that need to happen on both a micro and a macro level between the brother's descendants. It won't always be easy, but it could be rewarding.