It was love that motivated me to accompany Luna Lovegood on a dangerous mission.  We'd been inseparable for three years, and by now we were as much in love with each other as any two fourteen-year-olds could be.  As soon as we had met as Ravenclaw first-years, I undertook to protect her against any harm that may have befallen her.  At first it was only mean pranks played by students who were intolerant of her harmless eccentricities.  To be an effective protector, I was going to have to increase my magical powers, and who better to teach me to do so than Hermione Granger?  She was a year ahead of me and the brightest student in her year.  She was already tutoring several of her friends, but I managed to persuade her to tutor me and Luna as well by doing favours for her and her friends.  The spells Hermione taught us were already powerful when cast by a single person, but when Luna and I both cast the same spell at the same time and place, our combined spells were even stronger, powerful enough to undo any harm that her enemies could do to her, and they soon gave up and quit picking on her.

But now, near the end of our fourth year, Luna faced a danger far greater than a few naughty students: she had volunteered to accompany some of her Gryffindor friends, including Hermione, to the Ministry of Magic to rescue Sirius Black from the Dark Lord!  She didn’t have to ask me to come with her; there was no way I could have been kept from doing so.  The other students rode on thestrals, but I was afraid to ride an animal I couldn’t see; so I followed them on my broomstick.  When we got there, Sirius was nowhere to be found, but several Death Eaters suddenly confronted us, and they were soon joined by the Dark Lord himself!  We ran for the exit, the Dark Lord and his followers in hot pursuit.  I stayed at the back of the pack of students, casting the Protego spell behind me every few steps, and as a result, none of us got hurt except for Ron Weasley, who had been addled by some brains he had touched.

Suddenly we found ourselves trapped in a room with the Dark Lord and his Death Eaters!  Fortunately some members of the Order of the Phoenix, including Sirius Black, came to our rescue.  Thinking that they could manage without our help, we all hid behind various objects, but I soon saw that Sirius was in terrible danger!  He had foolishly challenged Bellatrix Lestrange to a duel.  She was a much better dueller than he was and he was standing in a very dangerous place.  I stepped out into the open and cast the Protego spell between Sirius and Bellatrix just in time to intercept a spell shooting out from each of their wands.  By this time, the other members of the Order had arrested all the Death Eaters except for Bellatrix.  Finding themselves overmatched, the Dark Lord and Bellatrix disapparated.

"Why did you do that?" Sirius rounded on me.  "I could have had her.  Her spell wasn't Avada Kedavra; the flash of light from her wand was red, not green."

"No, she would have had you," I replied.  "You were standing right in front of the veil.  Luna, who has seen death, told me that she heard the voices of the dead through the veil.  Any spell that hit you would have knocked you through the veil and you would have joined the dead."

Sirius thought for a while, and then said, "Well, young man, it seems that you saved my life, and I thank you.  Is there anything I can do for you in return?"

"Yes, there is," I replied.  "I've heard that you're an Animagus, and I'd like you to teach me how to become one too."

"Gladly!" he said.  And then we all made the long trip back to Hogwarts.  Sirius could have apparated with the other members of the Order, but he decided to keep us company on the way back.  He too was afraid to ride on a thestral; so he rode with me on my broomstick.  He then appealed his conviction on the charges for which he had been incarcerated in Azkaban, and with Albus Dumbledore as his chief witness, he was cleared of all charges. 

It took me two years to learn how to transform myself totally into an animal.  In the meantime, Luna faced another danger from which I was to protect her, and this time I didn't need to use magic.  Every Christmas she used to go home to spend some time with her father Xenophilius, but this time, in our sixth year, I pleaded with her to stay at Hogwarts with me. "Now that the Dark Lord has taken over the Ministry, it's not safe to venture out of Hogwarts," I said.  "This is still the safest place to be."  After some hesitation, she agreed, and it was a lucky thing that she did.  When the students returned to Hogwarts at the end of the Christmas holidays, some of them told us that a gang of Snatchers had boarded the Hogwarts express on the way from Hogsmeade to King's Cross Station and searched for Luna!  Apparently the Dark Lord had wanted to use her as a hostage to make her father stop publishing articles in his newspaper, the Quibbler, in support of Harry Potter, the Dark Lord's greatest enemy.  I was relieved that she had avoided being captured and I was all the more determined to continue protecting her.

A couple of months later, I finally became a full-fledged Animagus.  A wizard can't choose his Animagus.  It reflects his personality, and my Animagus, a bonobo, reflects mine: intelligent and peaceful.  It was the very animal I had hoped it would be.  As an ape I could handle a wand.  Although I couldn't say an incantation, I had already learned how to cast non-verbal spells, and since nobody would suspect an ape of being capable of casting a spell, I could do so by surprise.  Of course, I didn't register right away, because that would have blown my cover to the Ministry, which was in the Dark Lord's hands.  Little did I know how soon I was going to have to use my newfound powers.