There are some disagreements over how much older then Iruka Kakashi is so I'm going with one year, seems to be a pretty common one.
Dewrder: Blynedd Vol III: The Life and Times of Umino Iruka and Hatake Kakashi
More often then not love is the result of many concusions over the corse of a lifetime.
R.F.Fischer
When Iruka was five he joined the Acadamy.
When Kakashi was six he graduated the Acadamy.
0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
When Iruka was nine he graduated the academy and barely survived the chunnin exams.
When Kakashi was fourteen he'd buried his teacher, his best friend, and more comrades then he could count.
0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
When Iruka was sixteen he survived…twice.
When Kakashi was seventeen he joined ANBU, his first assignment destroying the bodies of several chunnin nins killed by enemy ninjas.
0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
When Iruka was nineteen he said goodbye and started teaching at the academy.
0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
When Iruka was twenty-one he was still reeling from the loss of Itachi, concentrating on trying to keep his own darkness away.
When Kakashi was twenty-two he was an ANBU star, nearing legend.
0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
When Iruka was twenty-two, Sarutobi officially deactivated the hunters, saying ANBU could handle things, promising not to call them back unless absolutely necessary.
When Kakashi was twenty-three he started working twice as many missions as normal and cut through lightning with the attack he would make legendary.
0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
When Iruka was twenty-three he became a full time teacher at the Ninja Acadamy.
Naruto's in his class, he doesn't remember requesting it because he'd been drunk when he did, but Sarutobi's smile when he hands Iruka his class list is enough.
The old man had always tried to be everything he needed; it didn't hurt too much to make him proud.
Iruka had an amazing tolerance for pain
When Kakashi was twenty-four he was still in ANBU.
0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
When he was twenty five Iruka met a Jounin who managed to give him a headache without even having to speak.
When he was twenty six Kakashi met a chunnin who stopped his heart.
0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
When Iruka first learned who was going to be Naruto's jounin sensei, it was followed by a 'but if you would just take the bloody rank of jounin, its not like you'd have to take the test, you could be his jounin sensei!'
Iruka had stared at Sarutobi for a moment and it took the Hokage a moment to realize that it wasn't surprise, but that Iruka didn't have a clue what jounin he was talking about. He'd fallen out of his chair in shock at that realization and then laughed; leave it to Iruka to not know who one of the most famous ninjas in Konoha was.
Iruka didn't look impressed when Sarutobi told him who Hatake Kakashi was.
When Hatake Kakashi first learned about Umino Iruka, all he knew was that he'd heard Kurenai mention an Academy teacher by the same name.
He was completely unprepared for the young scared chunnin who swept Naruto up into his arms when the boy rushed back after passing Kakashi's exam to tell him. He'd remained in stunned silence as Iruka treated all four of them to ramen.
That night he decided he would like to get to know the chunnin better.
And then the exam came and any chance of that went straight to hell, laughing.
Kakashi felt like crying.
Iruka wanted to strangle him. That damn jounin should have listened instead of pushing the kids to fast, even if they jumped at the chance.
A jounin of Kakashi's rank and skill should now better, kids rarely think before acting.
Though Iruka's begun to notice, with a feeling of dread and dark amusement that Kakashi has a habit of acting the same way.
Oh, well, it really just proved his theory that jounin were overgrown children.
Finally, after all this time, proof!!!!
0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0o0
When Kakashi is 27 he finally gets the courage up to tell Iruka how he felt. The chunnins face went red, blue, white in that order.
Then he kissed Kakashi so passionately that the jounin fainted dead away.
What Kakashi finds really fucked up is that Iruka has more scars then he does and won't speak of where he got them.
...diwedd...