a looming thing upon my Sunday

There is a weighty task looming upon my Sunday. Sundays, thankfully, are still more magical to me than mundane, even though the magic takes a more tricky turn than what is customary.
Well. Let's go back to my looming thing. As a part of that glorious privilege to have a seat reserved in a college, there are the wicked things - assignments.
Rather like itches, really: amusing, distressing, and pleasant to scratch.

Mine, which looms like a gloomy Shadow - minus the scythe - is to alter the ending of a play. Hold the contentions. It does sound offensive to me too, initially. A little more, after I finished reading the play in question; I realised it had been written with a focus, an intention to represent something and more importantly, there is a reason why the ending had been made thus. And I felt a chill I have never been able to explain, similar to one I felt when I still wet my bed and woke in the morning recalling the promise I had made my mother the previous night that I would not wet my bed.
What does altering an ending constitute?
Sometimes it feels to constitute such wrongness as to - forgive the harshness of the phrase - soil somebody else's well-nurtured garden.

I have written this in an effort to appease myself a little, but I have been misled. My heart still hammers at the prospect.