User blog comment:Solstice962/Ivan Dreyar Is Actually The Good Guy??/@comment-7418318-20170504083833

Ivan had no clue what Lumen Histoire was beyond it being top secret and only supposed to be known to the guild masters.

Not to mention that Ivan very clearly stated that he wanted to crush Fairy Tail and make Makarov suffer. I even have the impression that this was Ivan's main goal, with Lumen Histoire just being a bonus thus I have a very hard time imagining Ivan as a good guy.

Even if he somehow suspected that Lumen Histoire could send you back in time (which he had no reason to), and he had a similar rationale as Ultear and believed that all the crimes he commits in this timeline will just disappear once he changes the past, he still acted out of spite which strongly hints at him being a shitty person in either case. But unlike Ultear, Ivan wasn't abducted and tortured as a child and neither was he raised by an evil person, so there's really no good excuse for his behaviour that we are aware of.

Though I'd like to point out that Fairy Heart by itself doesn't enable time-travel. It is just an infinite supply of magic power. What Zeref is really using to go back in time is his own vast knowledge and the Ravines of Time. FH just provides the immense amount of magic power necessary to activate this door through time, just like in the GMG the Eclipse Gate needed several years to siphon a sufficient amount of magic power from nearby mages to charge up enough to open a time-tunnel 400 years into the past.