YES, MASTAH!!!
....
Well let's see... Izumi and Ex are like... well it's a love-hate relationship. XD But seriously, Ex feels she needs to keep Izumi safe, but yet Izumi wants to protect her partner. Izzy doesn't hate the little pervert, but she does get very very annoyed at her. XD However, over all I think Ex is more protective and more like an older sister to Izumi that she'd care to admit.
Suki and Yama I believe are very good friends. I don't think either of them would go so far as to call each other sisters in any respect, but they do act like it... Yama, however, would be more like the younger sibling. Suki really acts like an older sister to Yama, but not so far as a mother; despite having to.... 'discipline'.... the wolf because of her eating habits. ^_^; This usually involves yelling and trying to keep food away from the pup. ^^;
There are a few times Mari and Carrie act like two sisters, but for the most part, they are just partners. Mari respects Carrie as Yama does Suki... but perhaps it's because they come from Germany and their practices and training is different, but for the most part, they're just partners. Don't get them wrong, however... they are close, and if you mess with one, you will get the wrath of the other...
Shugotenshi and Kurotatsumon are the most obvious. While Kuro does take orders from Shugo, Shugo still acts as the leader of the two... Kuro is also very protective of Shugo and has been with him since he was 6?. Because of that, Shugo grew up with Kuro always by his side, and as that happened, the relationship shifted. When he was still young, Kuro always acted like a big brother and would protect him when he had to. Now that Shugo is 19, it's almost reversed. Neither of them would want to get rid of the other... they are very close. One would be hard-pressed to separate them for long periods of time. Barring death/deletion of one of them, there is nothing that has been able to or will keep them apart. They know each other well enough that both are closely connected. One singular time; each; one felt the other needed them in the situation they were facing at the time... and came to their aid.
Mitsu and Nekomon are hard to describe. It's easy to say that Nekomon is very.... as Cam put it... "Yes Mastah!" ^^; Yet... Mitsu does not have the aura of
being a 'Master' to the cat Digimon about her... They act as partners, but still... Mitsu still gives the orders, and Nekomon willingly follows the girl's commands. No matter how strange they are... or how much they seem to make no sense. Nekomon completely trusts Mitsu. I think it's safe to say that Mitsu also trusts Nekomon.
Nn.... beyond that, I really ain't got much else to say. XD