Mr. Grim Reaper's heart.

When everyone thought Pompom'd passed away something miraculous happened:

Mr. Grim Reaper buttoned his cloak and put aside his scythe.
With Captain Hook's hook, he went fishing for the first time in Soul Collection history.
He grabbed Pompom's line heart and gave it a good shake to bring it back to life.

Pompom's ears reddened, sunrays hit his newborn face. He breathed in the nostalgic, familiar smells and he knew, deep inside, that Mr. Grim Reaper has a heart, afterall...