We are looking at chapter 2, Mishnah 6 in Tractate Kerisos, the last of three mishnayos dealing with a shifchah charufah and the laws surrounding this situation. The structure of these three mishnayos is somewhat surprising: in the middle of Mishnah 4, the Mishnah began listing the differences between a shifchah charufah and other forbidden relationships; in Mishnah 5, it went back and defined what constitutes a shifchah charufah; and now, in Mishnah 6, we return to the topic opened in Mishnah 4 - the difference between the standard laws of forbidden relationships and the laws of forbidden relations with a shifchah charufah.
Even more surprising is that although the primary goal of the Mishnah is to contrast the law of other forbidden relationships with the law of a shifchah charufah, there is no mention of a shifchah charufah in it at all. The Mishnah lists three general principles that apply to forbidden relationships and forbidden relations, while the punchline is left unsaid, as it were: none of this applies to a shifchah charufah, which differs from all the rest.
The fundamental rule regarding a shifchah charufah, in contrast to the laws we will list now, is that even though the two participants receive different punishments - she receives lashes, and he must bring an asham shifchah charufah offering - it is a package deal: he is obligated to bring the asham only if she is liable, and vice versa. The matters are intertwined, and if for any reason she is not liable, he is also not liable.
The three laws in the Mishnah:
Adult and minor: In all other forbidden relations, if one participant is an adult (bar mitzvah) and the other is a minor - the adult is liable and the minor is exempt.
It should be noted that regarding forbidden relations, for the act to be considered a valid act constituting a forbidden relation, the boy must be at least nine years old. If the boy is under the age of nine, even though he participated in the act physically, it is not considered the technical fulfillment of the prohibition, but rather a completely different matter. Similarly, if the girl is under the age of three, there is no halachic act of forbidden relations here, but rather another matter that does not fit this technical definition. We will return to this point at the end of the Mishnah, as it raises an interesting question.
Awake and asleep: If one participant is awake and the other is asleep - "he-yashen patur" - the sleeping one is exempt. The sleeping person is not considered a participant in the act, and their status is that of someone coerced; therefore, they are not liable for anything, not even a chatas, as they are not in the category of an unintentional offender who is obligated to bring an offering. Meanwhile, the awake person is liable for whatever punishment fits their action.
Unintentional and intentional: If one participant acted without knowing they were violating the halachah, and the other knew it perfectly well - "ha-shogeg be'chatas ve-ha-mezid be'kareis" - the unintentional offender is liable for a chatas and the intentional offender for kareis. In every prohibition carrying the penalty of kareis, one who acts unintentionally brings a chatas, and one who acts intentionally (without witnesses and warning, which would have obligated a more severe punishment) is liable for kareis. We find that both receive different punishments.
The unsaid punchline:
All of the above does not apply to a shifchah charufah. There, if she is exempt - he is also exempt, and vice versa; it is an all-or-nothing package deal. He himself is not subject to many conditions, but she needs to be the appropriate age, meaning twelve years old, making her liable for lashes, she needs to be awake, and she needs to do it intentionally, knowing that this act is forbidden. If she did it unintentionally, she is not liable for lashes, and therefore he is not liable for an asham either. With this, the Mishnah concludes, and with this, the chapter concludes.
The dispute between the Rambam and the Raavad:
An interesting halachic dispute was stated regarding a case where she meets all the conditions - she is an adult, and acted intentionally and deliberately - while the boy is not yet bar mitzvah and cannot be obligated to bring an offering, but he is over the age of nine, so she is liable for the forbidden act. What is her halachic status?
The opinion of the Raavad: Since he cannot be obligated to bring an offering due to his minority status, she is also exempt from lashes, as this is a package deal.
The opinion of the Rambam: She receives lashes. Because of his minority status, he cannot bring an asham now, but when he reaches the age of bar mitzvah he will bring the asham.
In summary: This Mishnah lists three laws that apply to all forbidden relations - the adult is liable and the minor is exempt, the sleeping person is exempt and the awake person is liable, the unintentional offender is liable for a chatas and the intentional offender for kareis - and in all of them the punishments are separate and not dependent on one another. The unsaid punchline is that with a shifchah charufah the law is the opposite: the liability of one depends on the liability of the other, acting as a package deal. On the borderline of this concept, the Rambam and the Raavad disagree in a case where she is an adult and he is a minor who has passed the age of nine: according to the Raavad she is also exempt from lashes, while according to the Rambam she receives lashes, and he will bring his asham once he reaches the age of mitzvos.