"Here you will find me,
Though I will not be here.
My memories are told,
To those I hold dear."
-------------------------------
"An ever-lasting shape,
With an ever-changing nature,
You've never before seen,
Such a formidable creature."
-------------------------------
"Two paths here interwine,
An oath of loyalty sworn,
From the bottom of my heart,
A relationship is born"

The above three riddles are to be solved individually, and then a common link is to be found between them all. Each riddle may refer to an event/person/item, but I'm not saying which.

Enjoy!