The relation which exists where one person has undertaken an obligation and another person is also under the obligation or other duty to the obligee, who is entitled to but one performance, and as between the two who are bound, one rather than the other should perform. The surety’s liability to the creditor or promisee of the principal is said to be direct, primary and absolute; in other words, he is directly and equally bound with the principal. The creditor may proceed against any one of the solidary debtors. (Agro Conglomerates, Inc. vs. CA, G.R. No. 117660, 18 December 2000)