If that's the backstory the two of you wind up going for, perhaps you'd like joint ownership of a Halfling slave girl and her massive, overpowered Tiger animal companion/mount?
Okay, so, basic build...
Well, right off the bat, Devoted Tracker
is a feat made for a Paladin/Ranger multiclass character. The prerequisites are such that you can qualify for it without any levels in Ranger, but that Smite Evil requirement would necessitate levels in Paladin, which obviously wouldn't be very fitting for this game. One could switch that over to Smite Good, which would allow one of the evil variant Paladins to qualify, but they have codes of conduct centered pretty heavily around dominance and taking charge, which tends to clash pretty heavily with the whole 'Halfling slave girl' part of the character concept.
If we're already making changes to Devoted Tracker, I think that a Scout variant called the Light Cavalry Scout from Dragon Magazine 346 would be extremely fitting for the character concept I've got. It loses Fast Movement, Camouflage, Hide in Plain Sight, and Free Movement, and in exchange gains a Special Mount that gains bonuses as a Paladin's mount does, save for the fact that it loses the ability to Share Spells and Command other creatures of its kind that Paladin mounts get, and instead gains Fast Movement, Trackless Step, and Free Movement abilities, as the Scout class features. Assuming that whatever DM we get would be okay with this, and with letting me get a customized version of Devoted Tracker that a Light Cavalry Scout could qualify for...
Race: Strongheart Halfling
Classes: Light Cavalry Scout 5/Beastmaster 1/Wild Plains Outrider 1/Halfling Outrider 1
Traits would be Slow and Uncivilized, Flaws would also be Slow and No Time For Book Learning, cutting my character's land speed down to 5 feet per round, making her illiterate and giving her penalties to Diplomacy, Bluff, Gather Information and all Knowledge skills except Knowledge (Nature), but giving her +1 hp per level and bonuses to Handle Animal and Wild Empathy.
STR - 6
DEX - 14
CON - 14
INT - 14
WIS - 14
CHA - 16
Both stat adjustments from level up would go to Charisma.
For feats, since Strongheart Halflings trade in the normal Halfling save bonus for a bonus feat, I should have quite a few to select... Too bad most of them are going to be spent on prerequisites.
F) Skill Knowledge
(used to pick up Handle Animal as a class skill)
B) Bareback Soul
1) Skill Focus (Handle Animal)
3) Mounted Combat
B) Track (Scout bonus feat)
5) Mounted Archery
7) Devoted Tracker (or customized variation)
And finally, for the mount itself...
Magebred Tiger (Swift Breed, bonus feat is Multiattack)
Gains bonuses for 5th-level Paladin mount due to being stronger than normal mount, and 5th-level Animal Companion. (+4 bonus HD, +6 natural armor, +2 Str, +1 Dex, Int 6)
10,000 gp of starting wealth spent on Feathered Wings fiendish graft for Tiger, granting flight speed at double the Tiger's land speed at average maneuverability.
(Champions of Valor allows for characters of any race or creature type with the Celestial-Attended Birth background to select this feat; Perhaps reflavoring it as a Fiend-Attended Birth would be appropriate?)
3) Improved Natural Attack (Bite)
5) Improved Natural Attack (Claw)
7) Power Attack
9) Improved Flight
(improves maneuverability to good)