Meet with an attorney ... because you are unrelated, unfortunately, your options are very limited.
FORMER IMMIGRATION LAW PROFESSOR -- LEGAL DISCLAIMER: This answer is offered for informational purposes only. It does not constitute an attorney-client relationship.
There are various things to consider such as your relationship to the individual, your current status, the individual's country of nationality, the individual's manner of entry, etc. I would consult with an attorney to divulge this information to determine the best course of action for you.
This information is for informational and educational use only and does not establish an attorney-client relationship.
It depends on exactly what you mean by "sponsor"
You should retain an experienced immigration lawyer, whether myself or one of my colleagues, to review all the facts, advise you, and handle the case.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.