Unmasking Acrostic

Readily it comes to me,
Easily, like a skin I slip into,
Judiciously chosen for comfort.
Even when unsought, it sits
Close by, ready to offer itself.
Take nothing for granted,
It whispers. Question all motives.
Overt or hidden, it never leaves,
Never leaves me be.

Some days, slow days, it seems
Easy-going as though, for that moment, it might
Not bother anyone. Trickster.
Sly thing. No sooner am I at ease than
It strikes, threatening an abyss,
Taunting with its silent, unfathomable prospects:
If x now, then surely y is next.
Vehement in its certainty,
Entertaining no doubt.

Do you see this happen on my face?
You may do, and wonder at my sinking.
Sulking, my family called it;
Perhaps they were right. It looks like that,
How the face contorts to display the heart’s trenches.
Otherwise unseen, the narrow fellow sneaking in the grass,
Reticulated, spreading
Its nets, its networks, through a whole body,
A system of knots nigh on impossible to untie.