He’s looking at a third degree felony, and that doesn’t include any possible statutory rape issues if they have a mutual agreed upon intimate relationship given both their ages.
Florida State 787.03 Interference with custody.-- (still applies if they leave state)
(1) Whoever, without lawful authority, knowingly or recklessly takes or entices, or aids, abets, hires, or otherwise procures another to take or entice, any child 17 years of age or under or any incompetent person from the custody of the child or incompetent person's parent, his or her guardian, a public agency having the lawful charge of the child or incompetent person, or any other lawful custodian commits the offense of interference with custody and commits a felony of the third degree, punishable as provided in s. 775.082, s. 775.083, or s. 775.084.
(4) It is a defense that:
(a) The defendant reasonably believes that his or her action was necessary to preserve the child or the incompetent person from danger to his or her welfare.
(b) (doesn’t apply to this case)
(c) The child or incompetent person was taken away at his or her own instigation without enticement and without purpose to commit a criminal offense with or against the child or incompetent person.
(b) In order to gain the exemption conferred by paragraph (a), a person who takes a child pursuant to this subsection must:
1. Within 10 days after taking the child, make a report to the sheriff's office or state attorney's office for the county in which the child resided at the time he or she was taken, which report must include the name of the person taking the child, the current address and telephone number of the person and child, and the reasons the child was taken.
2. (applies to parental custody issues)
3. Inform the sheriff's office or state attorney's office for the county in which the child resided at the time he or she was taken of any change of address or telephone number of the person and child.