Although her actions in Scene 1 in refusing to give up the governor's baby to the Prince can be interpreted as stubborness rather than anything else, it is clear that Grusha develops into a very heroic figure as the play progresses. This is shown most clearly in the way that she willingly repeatedly risks her own life to try and save the life of Michael, and the way that she comes to identify herself as Michael's mother. This is shown in numerous places, most importantly the famous test of the chalk circle towards the end of the play, where her love for Michael shows her to be the child's "true" mother, even if this defies genetics. However, it can also be shown in the way that she repeatedly risks her own life to ensure Michael's survival. This can be seen in Scene 3, where Grusha crosses a rotten rope bridge to escape the two Ironshirts that she has already come to blows with in order to save Michael from certain death. Note what she sings to the child to calm him as she begins to cross the precarious bridge:

Of every four morsels 
You shall have three.
I would that I knew
How big they will be!

Grusha therefore proves beyond a doubt that she is a heroic figure in this play through the way that she repeatedly risks her own life and sacrifices her own comfort and safety in order to provide for Michael, who is not her own child, and to keep him safe. This is something that is clear from the outset of the play: Grusha, in spite of the political turmoil that surrounds her, could have had an easy life had she left the Governor's son to his fate, but she refused to leave him alone and embarks on an escape with him, eventually proving her heroic status by showing her greater love for Michael.