Disclaimer: I do not own Fairy Tail
It's been 550 years since he was allowed near the Tenrou tree. Every time he tried, an unseen force seemed to thwart his attempts. However, Zeref felt in his bones that he would be allowed to venture there today. He was right.
The tree had not changed, the only thing other than Zeref himself that have withstood the trials of time. His eyes, however, were fixed on something else entirely.
"I've missed you," Zeref said as he walked hesitantly forward, stopping in front of a slab of marble. The once white and pristine stone had many cracks across its surface, yet another victim to the passage of time.
"It's been a long time, hasn't it?" he said softly, "Yet I still can't forget you. Sighing, he ran his pale, slender hands through his dark locks.
"I wish I could hate you, but I can't. Even though you broke your promise… it was my fault. You know, sometimes I wonder what would have happened if you left me like I told you to that day. None of this would have happened, and we'd all be six feet under now," Zeref chuckled, "But then again, you never did listen, did you Mavis?"
Casting his eyes to the ground, "I did bad things," he mumbled, "I still do. I've killed and tortured countless people; they call me the evilest mage of all time and… I don't really blame them."
He fell silent, relieving the joy-filled days he had spent with Mavis, from the day they first met to that terrible last day 550 years earlier. If one looked closely, a faint ghost of a gentle, peaceful smile could have been seen, something that hadn't graced his lips in over half a century.
Finally, Zeref let out a long breath, "Thank you for everything," he said, "Although I want to forget - just like the world did - of the past, I truly cherished your company. I know I would never be allowed to come back here again but… it was nice talking to you, Mavis."
Leaning forward, he gently pressed his lips against the marble's cool surface. As he strode away, Zeref swore he heard a youthful, lilting voice in the wind.
"Even if the world will never forgive you, I forgive you, Zeref."
And so, a man visited the only one he cared about for the last time, that day under the Tenrou tree.