
thelemonache |

Hi friends :)
Do you flank while in your opponents square, regardless of whether you spent panache to enter someones square? for example, could a tiny fox spend all day entering squares the old fashioned way and count as flanking with the second paragraph of the deed below? I feel like you would based on how it reads, but when I read how the deeds ability itself is defined, it makes me think it might only work while activated with panache.
Deeds read like this:
Deeds
Swashbucklers spend panache points to accomplish deeds. Most deeds grant the swashbuckler a momentary bonus or effect, but some provide longer-lasting effects. Some deeds remain in effect while the swashbuckler has at least 1 panache point, but do not require expending panache to be maintained. A swashbuckler can only perform deeds of her level or lower. Unless otherwise noted, a deed can be performed multiple successive times, as long as the swashbuckler has or spends the required number of panache points to perform the deed.
The Mouser deed reads like this:
Underfoot Assault (Ex): At 1st level, if a foe whose size is larger than the mouser’s is adjacent to her and misses her with a melee attack, the mouser can as an immediate action spend 1 panache point to move 5 feet into an area of the attacker’s space. This movement does not count against the mouser’s movement the next round, and it doesn’t provoke attacks of opportunity. While the mouser is within a foe’s space, she is considered to occupy her square within that foe’s space.
While the mouser is within her foe’s space, the foe takes a –4 penalty on all attack rolls and combat maneuver checks not made against the mouser, and all of the mouser’s allies that are adjacent to both the foe and the mouser are considered to be flanking the foe. The mouser is considered to be flanking the foe whose space she is within if she is adjacent to an ally who is also adjacent to the foe. The mouser can move within her foe’s space and leave the foe’s space unhindered and without provoking attacks of opportunity, but if the foe attempts to move to a position where the mouser is no longer in its space, the movement provokes an attack of opportunity from the mouser.
This deed replaces opportune parry and riposte.

AwesomenessDog |

You can be in a creatures space regardless of the mouser ability, especially if you have a tiny character as an example. The ability to dodge into their space is completely separate from the change to normal rules to how being in an enemy square works (for size different creatures) and flanking in the second paragraph. They both come from the same granted ability, but think of them as two separate abilities.

Mysterious Stranger |

Keep in mind that normally you cannot move through an opponent’s square unless they are helpless, or you are three sizes smaller. Also a fine, diminutive or tiny creature can move through an opponent square, but provokes an attack of opportunity doing so. The rules also state you cannot end your movement in an opponent square unless they are helpless or tiny or smaller.
Assuming the tiny fox is a swashbuckler with the deed they would be considered flanking if they are in the opponents square, and if both the target and the fox are adjacent to an ally of the fox. One thing to keep in mind is that if you don’t spend the panache, you will provoke an AoO for moving into the square.

VoodistMonk |

You do not need to spend Panache every round to get the bonus, if that's what you're asking. That second paragraph is something that occurs any time the Mouser is up in someone's business... the immediate action spending Panache described in the first paragraph is how you get up in their business.
Round 1: adjacent enemy misses Mouser, and Mouser spends Panache to enter enemy's space... any adjacent allies are now flanking the enemy with the Mouser.
Round 2: if the Mouser is still in the enemy's space, then everyone adjacent is still flanking the enemy with the Mouser.
As long as the Mouser shares the space of the enemy, then that enemy takes the -4 penalty, and adjacent allies are considered to be flanking the enemy with the Mouser in the enemy's space. The Mouser could have spent their very last point of Panache to enter the enemy's space, and the deed will still be active as long as the Mouser is in the same space as the enemy... even though the Mouser is now completely out of Panache.
The Mouser could have used a completely different method, like the Swarm Fighter's Share Space or the Vexing Dodger's Limb Climber ability, to occupy the same space as the enemy, not spending any Panache at all... and the enemy will still take the -4 penalty, and adjaceny allies will still be considered flanking.

thelemonache |

Keep in mind that normally you cannot move through an opponent’s square unless they are helpless, or you are three sizes smaller. Also a fine, diminutive or tiny creature can move through an opponent square, but provokes an attack of opportunity doing so. The rules also state you cannot end your movement in an opponent square unless they are helpless or tiny or smaller.
Assuming the tiny fox is a swashbuckler with the deed they would be considered flanking if they are in the opponents square, and if both the target and the fox are adjacent to an ally of the fox. One thing to keep in mind is that if you don’t spend the panache, you will provoke an AoO for moving into the square.
I think we agree, but the way you worded it confused me a bit, so I wanted to link the rules for anyone joining the conversation. :)
thanks for the input everyone!
Movement in combat:
Very Small Creature
A Fine, Diminutive, or Tiny creature can move into or through an occupied square. The creature provokes attacks of opportunity when doing so.
Square Occupied by Creature Three Sizes Larger or Smaller
Any creature can move through a square occupied by a creature three size categories larger than itself.
A big creature can move through a square occupied by a creature three size categories smaller than it is. Creatures moving through squares occupied by other creatures provoke attacks of opportunity from those creatures.

AwesomenessDog |

Another gentle reminder of the "stealth" update (pun intended) whereby the size difference was reduced to 2 sizes or wider.
Hiding Behind Another Creature:
Large bodies that break your opponent’s line of sight can sometimes be just as useful as darkness for hiding your position.
Special: Normally the soft cover provided by other creatures is not sufficient to allow you to attempt a Stealth check. Soft cover provided by creatures at least one size category larger than you does allow you to attempt Stealth checks against other creatures not already aware of your presence at a –10 penalty. If the creature providing the cover knows which square you occupy and is trying to avoid concealing you, this penalty increases to –20.
You can also hide from a creature by staying under its own body if it is at least two size categories larger than you and you are in its space. Such attempts also take a –10 penalty, which increases to a –20 penalty if the creature is aware you are in the area. If the creature moves away from you, you are automatically revealed, unless you have readied an action to move with it.

thelemonache |

Another gentle reminder of the "stealth" update (pun intended) whereby the size difference was reduced to 2 sizes or wider.
Giant Hunter's Handbook wrote:Hiding Behind Another Creature:
Large bodies that break your opponent’s line of sight can sometimes be just as useful as darkness for hiding your position.
Special: Normally the soft cover provided by other creatures is not sufficient to allow you to attempt a Stealth check. Soft cover provided by creatures at least one size category larger than you does allow you to attempt Stealth checks against other creatures not already aware of your presence at a –10 penalty. If the creature providing the cover knows which square you occupy and is trying to avoid concealing you, this penalty increases to –20.
You can also hide from a creature by staying under its own body if it is at least two size categories larger than you and you are in its space. Such attempts also take a –10 penalty, which increases to a –20 penalty if the creature is aware you are in the area. If the creature moves away from you, you are automatically revealed, unless you have readied an action to move with it.
with this stealth rule, can you standard action attack, move action hide underneath him/her? that sounds worthy of a high stealth hehe