Situation:
Hiraga Saito, the main male character from Zero no Tsukaima, is from Earth (specifically Tokyo, Japan).He was Summoned as a Familiar of Loise, a magician which made him travel from his world to Loise´s.
Power:
There are Runes inscribed into Saito's hand as a result of his being bound to Louise. They read geboundolf or Gundolf meaning Gandalfr.
These runes glow when his Gandalfr powers activate. As a Gandalfr, Saito has the ability to use any object that was made with the intent of being used as a weapon at an extremely high level of skill. He also becomes significantly stronger, faster and tougher. Even weapons that he had never touched before, such as an M-72 rocket launcher and a World War II Zero Fighter, can be instantly understood and utilized. This physical augmentation fades more or less instantly when he stops using the power, which can result in him falling unconscious if he'd been wounded previously.
His partner, the talking sword Derflinger, was also the partner of the Gandalfr from six-thousand years ago. His advice and comments never reflect well on Saito. Saito protects Louise because he is her familiar, and it is later shown that he has feelings for her as well, claiming "All that he is good at is protecting her". He is revealed to be a Gandalfr, a familiar who exists to protect a Void Wizard as they cast their spells
Way of Living:
The series constantly implies him being a pervert and sometimes he does think exactly like one, but justifiably, he is a young single guy who isn't married to anyone. Louise just enforces an ownership type arrangement over Saito implying she is owed Saito's feelings. It is later revealed that Saito has feelings for Louise and even says it openly to her.
Saito also has a bit of a troublesome and somewhat complicated tendency of getting involved with women. Strange and oddly sexual things happen when he seemingly becomes intimate with another girl. When he meets or speaks to an attractive girl, he is often only noticing her chest in a few instances . This is actually one of the main reasons why Louise treats him so poorly as he is expected to be perfect in every way in her childish mindset.
Although he acts a bit perverted at times, this does not mean that he does not think of Louise. Similar to how she feels whenever he is becoming intimate with another girl Saito can get very upset when it comes to Louise and other men. He uses the name "My Louise" several times in the light novels when he feels jealous toward other guys. This is definite evidence of his strong feelings for Louise.
END:
In Zero no Tsukaima F, the final episode, he gets married to Louise. He also traveled back to Japan, accompanied by Louise because of her teleport magic.