Nissa regained herself on Zhalfir with dead Phyrexian metal still attached and Chandra beside her. Cleansing returned her mind but not the effortless connection to planes that had defined much of her adult life. Recovery required physical work, patience and an identity no longer organised around being the person who could always depart.
Chandra wanted celebration because survival felt impossible enough to deserve it. Nissa kept clearing wreckage because unfinished labour gave shape to guilt. Their different responses were not opposites so much as attempts to manage the same fear: that one would move on before the other could trust the reunion.
The loss of Nissa’s spark made Chandra’s remaining ability a problem neither could solve through reassurance. Chandra still had obligations elsewhere, including finding Ajani. A promise never to leave would be false; leaving without a new way back could repeat the separation they had only just survived.