If I have Shadow Parasite and his strength has been increased, would he retain that strenght if his text box was subsequently blanked

Response: After a character's STR is reduced by X, Shadow Parasite gets +X STR until the end of the phase

Lets say that during the challenge phase, I reduce a characters strength and S-P gets that strength - his strength is now +2

Someone plays, e.g. Fortified Position

Treat all characters in play as though their printed text boxes were blank (except for Traits).

What is S-P strength now?
(I assume he retains the strength)

Once triggered, a lasting effect continues through its set duration regardless of what happens to the text later.

Look at it this way: if you raised the SP's STR "until the end if the phase" with a +X STR event or location, would it matter what subsequently happened to the text on the event or location?